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AGRICULTURAL  LIBRARY 

UNIVERSITY  OF  CALIFORNIA 

CITRUS  RESEARCH  CENTER  AND 

AGRICULTURAL  EXPERIMENT  STATWH 

'  RIVERSIDE,  CALIFORNIA 


OF 


LELAND   STANFORD   JUNIOR   UNIVERSITY 
UNIVERSITY  SERIES 

No.  2 


THE 
OPISTHOBRANCHIATE  MOLLUSCA 

OF  THE 

BRANNER-AGASSIZ  EXPEDITION 
TO  BRAZIL 

BY 

FRANK  MACE  MACFARLAND 

Professor  of  Histology 
Leland  Stanford  Junior  University 


WITH  PLATES  I -XIX 


STANFORD  UNIVERSITY,  CALIFORNIA 

PUBLISHED  BY  THE  UNIVERSITY 

1909 


UNIVERSITY  SERIES 

No.  1 

Inheritance  in  Silkworms,  I.     Vernon  Lyman  Kellogg,  Professor  of 
Entomology.     89  pp.,  4  pi.     1908. 


LELAND  STANFORD  JUNIOR   UNIVERSITY  PUBLICATIONS 

UNIVERSITY  SERIES 

No.  2 


THE 
OPISTHOBRANCHIATE  MOLLUSCA 

OF  THE 

BRANNER-AGASSIZ  EXPEDITION 
TO  BRAZIL 

BY 

FRANK  MACE  MACFARLAND 

Professor  of  Histology 
Leland  Stanford  Junior  University 


WITH  PLATES  1-XIX 


STANFORD  UNIVERSITY,  CALIFORNIA 

PUBLISHED  BY  THE  UNIVERSITY 

June.  1909 


CONTENTS 

PAGE 

INTRODUCTION 5 

LIST  OF  OPISTHOBRANCHIATE  MOLLUSCA  COLLECTED  BY  THE 

BRANNER-AGASSIZ  EXPEDITION 6 

LIST  OF  OPISTHOBRANCHIATE  MOLLUSCA  THUS  FAR  RE- 
CORDED FROM  THE  COAST  OF  BRAZIL  ....  7 

DETAILED  DESCRIPTIONS  OF  THE  SPECIES  COLLECTED — 

1.  Tethys  dactylomela  (Rang) 14 

2.  Tethys  cervina  Dall  and  Simpson 38 

3.  Pleurobranchus  agassizii  sp.  nov 59 

4.  Discodoris  branneri  sp.  nov.          66 

5.  Discodoris  voniheringi  sp.  nov 73 

6.  Peltodoris  greeleyi  sp.  nov 84 

7.  Spurilla  braziliana  sp.  nov 91 

LITERATURE  CITED 100 

EXPLANATION  OF  PLATES 105 


THE  OPISTHOBRANCHIATE  MOLLUSCA  OF 

THE  BRANNER-AGASSIZ  EXPEDITION 

TO  BRAZIL.* 

During  the  explorations  of  the  Branner-Agassiz  expedition 
to  Brazil  in  1899  a  small  collection  of  Opisthobranchiate  Mollusca 
was  made  by  Mr.  A.  W.  Greeley,  a  member  of  the  expedition. 
These  were  turned  over  to  the  writer  for  study,  and  the  results 
obtained  are  embodied  in  the  present  paper.  The  Opisthobranchs 
of  the  Brazilian  coast  are  but  little  known,  no  systematic  effort 
having  been  made  as  yet  to  collect  and  study  them,  and  it  is  only 
occasionally  that  reference  to  them  is  to  be  found  in  the  literature 
upon  the  subject.  Several  shell-bearing  Opisthobranchs  have  been 
described  by  various  authors,  but  the  naked  members  of  the  group 
have  received  but  scant  attention,  and  Von  Ihering  is  practically 
V  the  only  author  who  has  examined  the  Brazilian  forms.  His  list 

-  and  description  of  six  species  of  Nudibranchs  published  in  1886, 

-  •  has  remained  for  twenty  years  with  but  scanty  additions. 

The  collection  made  by  Mr.  Greeley,  though  but  small  and 
'  made  without  any  especial  attention  to  the  group,  adds  seven  to  the 
'•*  list  of  species  thus  far  known  from  Brazilian  waters,  and  is  an 
indication  of  the  results  which  careful  and  extended  collecting  in 
.  those  regions  might  secure.  Two  shell-bearing  Opisthobranchs 
were  also  found  in  the  collection  made  by  Mr.  Greeley  and  studied 
by  Professor  W.  H.  Dall,  and  are  listed  in  his  "Mollusks  from  the 
Vicinity  of  Pernambuco,"  Proceedings  of  the  Washington  Acad- 
emy of  Sciences,  III.  1891.  p.  139-147.  These  are  added  to  the 
list  given  in  the  present  paper. 

There  is  so  little  known  about  the  structure  of  the  Opistho- 
branchs from  this  region  that  a  somewhat  detailed  examination 
of  the  collection  in  this  ^espect  has  seemed  warranted,  especially 
since  external  characters  afford  so  meagre  a  basis  for  classifi- 
cation in  this  group.  Unfortunately  the  number  of  specimens 
secured  is  but  small,  so  that,  in  most  cases,  the  minute  anatomical 
study  was  hampered  by  the  lack  of  material.  No  notes  save  those 

*  Other  reports  upon  the  collections  made  by  the  Branner-Agassiz  Expedition 
have  appeared  in  Volume  III  of  the  Proceedings  of  the  Washington  Academy  of 
Sciences. 


6  OPISTHOBRANCHIATA   OF   BRAZIL 

of  locality  and  date  were  taken  by  the  collector,  so  that  nothing 
can  be  given  as  to  the  color,  or  form  of  body  in  the  living  animal. 
In  the  study  of  the  collection  most  of  the  specimens  have  been 
dissected,  and  many  parts  have  been  cut  into  serial  sections,  or 
otherwise  prepared  for  microscopical  study.  All  of  these  prepara- 
tions, as  well  as  the  animals  themselves,  or  what  remains  of  them, 
are  deposited  in  the  Zoological  Museum  of  the  Leland  Stanford 
Junior  University,  and  their  serial  numbers  are  given  under  each 
species  in  the  present  paper. 

The  following  is  a  conspectus  of  the  seven  forms  discussed 
in  the  following  pages. 

Order  OPISTHOBRANCHIATA. 
Suborder  TECTIBRANCHIATA. 
Tribe  Aplysoidea. 

Family  Aplysiidae. 

1.  Tethys  dactylomela  (Rang). 

2.  Tethys  cervina  Dall  and  Simpson. 
Tribe  Pleurobranchoidea. 

Family  Pleurobranchidae. 

3.  Pleurobranchus  agassizii  sp.  nov. 

Suborder  NUDIBRANCHIATA. 
Tribe  Doridoidea. 

Family  Dorididae. 
Subfamily  Discodoridinae. 

4.  Discodoris  branneri  sp.  nov. 

5.  Discodoris  voniheringi  sp.  nov. 
Subfamily   Diaululinae. 

6.  Peltodoris  greeleyi  sp.  nov. 
Tribe  Aeolidoidea. 

Family  Aeolididae. 

7.  Spurilla  braziliana  sp.  nov. 

The  complete  list  of  the  Opisthobranchiate  Mollusca  of  the 
Brazilian  coast  thus  far  described,  together  with  those  above 
listed  is  as  follows.  Those  marked  with  an  asterisk  are  deep 
water  forms,  i.  e.  100  fathoms  and  over,  and  are  of  wide  distri- 
bution throughout  the  Atlantic  Ocean. 


INTRODUCTION  7 

Order  OPISTHOBRANCHIATA. 
Suborder  TECTIBRANCHIATA. 
Tribe  Bulloidea. 

Family  Actaeonidae. 

i.  Actaeon  cumingii  A.  Adams. 

Rio  Janeiro,  A.  Adams,  Proc.  Zool. 

Soc.,  London,  1854,  p.  59. 
Family  Ringiculidae. 

*2.  Ringicula  peracuta  Watson. 

Off  Pernambuco,  350  fathoms.  Wat- 
son, Challenger  Gasteropoda,  p.  636. 
= Ringicula  nitida  Verrill.  Dall, 
Bulletin  Museum  Comp.  Zool.  Har- 
vard, XVIII,  1889,  p.  43. 
Family  Tornatinidae. 

3.  Tornatina  liratispira  Smith. 

Rio  Janeiro,  E.  A.  Smith.  Annals 
and  Magazine  Nat.  Hist.,  (4),  IX, 
P-  354- 

4.  Tornatina  canaliculata  (Say). 

Anchorage    off    Fernando    Noronha, 
7-25  fath.  Watson,  Chall.  Gasterop., 
P-  655- 
*5.  Retusa  ovata  (Jeffreys). 

Off  Pernambuco,  350  fath.  Watson, 

Chall.  Gasterop.,  p.  664. 
Family  Scaphandridae. 

*6.  Diaphana  seguenzae  (Watson). 

Off  Pernambuco,  350  fath.  Watson, 
Chall.  Gasterop.,  p.  646. 

7.  Cylichna  noronyensis  Watson. 

Anchorage  off  Fernando  de  Noronha, 
7-25  fath.  Watson,  Chall.  Gasterop., 
p.  666. 

8.  Cylichna  bidentata  (d'Orbigny). 

Canal  de  San  Sebastiao,  Von  Ihering. 
Revista  Museu  Paulista,  II,  1897, 
p.  169. 


OPISTHOBRANCHIATA   OF   BRAZIL 

Family  Bullidae. 

9.  Bulla  rubiginosa  Gould. 

Near  mouth  of  Rio  Janeiro  Harbor, 
Couth.  Gould,  U.  S.  Exploring 
Exp.,  XII,  Mollusca  and  Shells, 
1852,  p.  221. f 

10.  Bulla  striata  Bruguiere. 

Canal  de  San  Sebastiao,  Von  Ihering, 

Revista  Museu  Paulista,  II,   1897, 

p.  169. 
Mangosoules,      Managuas,      Mageio. 

Dall,  Proc.  Wash.  Acad.  Sci.,  Ill, 

1901,  p.  142. 
Family  Aceratidae. 

11.  Haminea  elegans  (Gray). 

?  Bulla  diaphana  Couthouy. 
Rio    Janeiro,    Gould,    Mollusca    and 
Shells,  U.  S.  Exploring  Ex.,  XII, 

1852,  p.  222.f 

Family  Hydatinidae. 

12.  Micromelo  undata  (Bruguiere). 
Goyana,  on  the  reef.  Dall,  Proc.  Wash. 

Acad.  Sci.,  Ill,  1901,  p.  142. 
Tribe  Aplysoidea. 

Family  Aplysiidae. 

13.  Tethys  livida  (d'Orbigny). 

Bay  of  Rio  Janeiro.  d'Orbigny,  Voy. 
dans  1'Amerique  Merid.,  V,  3,  1835- 
1843,  P-  206. 

14.  Tethys  braziliana  (Rang). 

Bay  of  Rio  Janeiro.  Quoy  and  Gai- 
mard.  Rang,  Histoire  Naturelle  des 
Aplysiens,  1828,  p.  55. 

15.  Tethys  dactylomela  (Rang). 

Mageio,  Alagoas.    Pernambuco. 


fThe  place  of  the  original  descriptions  of  Bulla  rubiginosa  Gould,  and  Bulla 
diaphana  Couthouy,  is  given  by  Gould  in  his  report  upon  the  Mollusca  of  the  U.  S. 
Exploring  Expedition  as  Proc.  Boston  Soc.  Natural  History,  III,  1849,  pp.  107  and  91 
respectively.  This  has  been  cited  in  several  recent  works,  e.  g.  by  Pilsbry  in  Tryon's 
Conchology,  XVI,  pp.  330  and  356.  I  am  unable  to  find  any  such  description  in  any 
of  the  earlier  volumes  of  the  Proceedings,  nor  any  earlier  descriptions  than  the  ones 
indicated  above. 


INTRODUCTION  9 

1 6.  Tethys  cervina  Dall  and  Simpson. 

Mageio,  Alagoas. 

17.  Notarchus  lacinulatus  (Couthouy). 

Rio  Janeiro  Harbor.     Gould,  U.   S. 

Explor.  Exp.  Moll.,  p.  223. 
Tribe  Pleurobranchoidea. 

Family  Pleurobranchidae. 

1 8.  Pleurobranchus  agassizii  MacFarland, 
sp.  nov. 

Riacho  Doce,  Alagoas. 

19.  Pleurobranchaea  inconspicua  Bergh. 

Mouth  of  Cotinguiba  River.  Bergh, 
Semper's  Reisen,  Wissenschaftliche 
Resultate,  VII:  Malacol.  Unters., 
IV,  I,  i,  1897,  p.  49- 

Suborder  NUDIBRANCHIATA. 
Tribe  Tritonoidea. 

Family  Tritoniidae. 

20.  Tritonia  cucullata  Gould. 

Coast  of  Brazil.     Gould,  U.  S.  Expl. 

Exp.  Moll.,  1852,  p.  308. 
=Marionia  occidentalis  Bergh.    Chal- 
lenger Exp.,  X,  1884,  p.  49,  La  Plata 

and  Buenos  Aires. 
Tribe  Doridoidea. 

Family  Dorididae. 

Subfamily  Archidoridinae. 

21.  Staurodoris  verrucosa  (Cuvier). 

Armagao,    Province   Santa    Catarina. 

Von  Ihering,  Jahrb.  deutsch.  Mala- 

kozool.  Ges.,  XIII,  3,  1886,  p.  230. 
= Staurodoris  januarii  Befgh.  Mai. 

Unters.,  XIII,  1878,  p.  583 ;  Sup.  H. 

I,  1880,  p.  37;  System.  1892,  p.  101. 
Subfamily  Discodoridinae. 

22.  Discodoris  branneri  MacFarland.   sp. 
nov. 

Riacho  Doce,  Alagoas. 


IO  OPISTHOBRANCHIATA   OF   BRAZIL 

23.  Discodoris    voniheringi    MacFarland. 
sp.  nov. 

Riacho  Doce,  Alagoas. 
Subfamily  Diaululinae. 

24.  Thordisa  ladislavii  (Von  Ihering). 

Armagao,  Prov.  Santa  Catarina.  Von 
Ihering,  Jahrb.  d.  Mai.  Ges.,  XIII, 
3,  1886,  p.  234. 

25.  Thordisa  dubia  Bergh. 

Rio  Janeiro  Harbor,  Rat  Island, 
Bergh,  Bull.  Mus.  Comp.  Zool. 
Harvard,  XXV,  1894,  p.  178. 

26.  Peltodoris    greeleyi    MacFarland.    sp. 
nov. 

Riacho  Doce,  Alagoas. 
Family  Doriopsididae. 

27.  Doriopsis  atropos  Bergh. 

Rio  Janeiro.   Bergh,  Jahrb.  d.  D.  Mai. 

Ges.,  VI,  1879,  p.  49. 
Tribe  Aeolidoidea. 

Family  Aeolidiadae. 
Subfamily  Aeolidianae. 

28.  Spurilla    braziliana    MacFarland,    sp. 
nov. 

Riacho  Doce,  Alagoas. 
Subfamily  Favorininae. 

29.  Phidiana  selencae  Bergh. 

Rio   Janeiro.      Bergh,    Beitraege   zur 
Kenntniss     der     Aeolidiaden.     VI. 
Verh.  d.  k.  k.  zool.-bot.  Gesellsch. 
in  Wien,  1878,  p.  560. 
Family  Pleurophyllididae. 

30.  Pleurophyllidia  muelleri  Von  Ihering. 
Armac,ao,  Prov.  Santa  Catarina,  Von 

Ihering,  Jahrb.  d.  Mai.  Ges.,  XIII, 
3,  1886,  p.  223. 

In  the  above  list  the  gymnosomatous  and  thecosomatous 
Pteropods  have  been  left  out  of  consideration.     Of  the  thirty 


INTRODUCTION  1 1 

species  enumerated,  the  Bulloidea  are  represented  by  twelve,  the 
Aplysoidea  by  five,  the  Pleurobranchoidea  by  two,  the  Trito- 
noidea  by  one,  the  Doridoidea  by  seven  and  the  Aeolidoidea  by 
three,  or  nineteen  Tectibranchs  and  eleven  Nudibranchs  as  the 
total  Opisthobranch  fauna  of  some  four  thousand  miles  of  coast 
line,  extending  from  4°  22^ '  N.  Lat.  to  33°  44'  S.  Lat.  Of 
these  all  the  Bulloidea  and  Aplysoidea  are  of  wide  distribution, 
many  of  them  occurring  throughout  the  North  Atlantic,  and 
others  in  the  Antilles.  It  is  readily  seen  from  this  that  our 
information  about  the  group  in  general,  and  the  Nudibranchs  in 
particular  makes  any  theorizing  as  to  distribution  for  the  present 
somewhat  premature. 

The  appearance  of  this  paper,  much  of  which  has  been  in 
manuscript  for  several  years,  has  been  delayed  by  other  duties. 
Six  months  spent  at  the  Zoological  Station  at  Naples  in  1903 
enabled  me  to  compare  and  dissect  the  Mediterranean  forms 
related  to  those  discussed  in  this  paper.  I  again  take  the  pleas- 
ant opportunity  of  expressing  my  most  cordial  appreciation  of  the 
many  kindnesses  shown  me  while  there  by  Professor  Dohrn  and 
his  staff,  as  well  as  to  the  Smithsonian  Institution  for  the  grant 
of  a  table  in  the  Station,  which  opened  these  privileges  to  me. 

In  the  systematic  arrangement  of  the  Opisthobranchiata 
adopted  in  the  present  paper  the  plan  of  Pelseneer  has  been 
followed  in  the  main.  The  characterizations  of  the  different  sub- 
divisions have  been  more  or  less  modified  from  those  of  Pilsbry, 
Pelseneer  and  Bergh  in  the  majority  of  cases. 


ORDER  OPISTHOBRANCHIATA. 

Marine  Euthyneura  with  aquatic  respiration;  the  ventricle 
of  the  heart  is  generally  anterior,  and  the  pallial  cavity,  when 
present,  is  widely  open.  There  is  a  marked  tendency  to  a  re- 
duction of  the  shell,  which  may  become  internal  or  disappear. 
In  the  naked  forms  spicules  are  sometimes  developed. 

SUBORDER  TECTIBRANCHIATA. 

Hermaphroditic  opisthobranchiate  Mollusca  provided  in  the 
adult  state  with  a  mantle  and  shell,  with  certain  exceptions ;  with 
one  branchial  plume  and  osphradium,  with  certain  exceptions. 

TRIBE  I.     BULLOIDEA. 

Shell  usually  well  developed,  sometimes  wanting,  external  or 
internal.  Operculum  seldom  present.  Pallial  cavity  well  devel- 
oped and  containing  the  usually  plicate  ctenidium.  Head  usually 
without  tentacles,  and  with  dorsal  surface  forming  a  shield, 
usually  separate  from  the  neck,  and  with  more  or  less  scalloped 
margins.  Edges  of  foot  continuous  with  its  ventral  face  and 
often  modified  into  fins.  Stomach  usually  with  chitinous  or  cal- 
cified masticatory  plates.  Visceral  commissure  usually  rather 
long.  The  monaulic  genital  duct  usually  connected  with  the  penis 
by  a  ciliated  groove. 

TRIBE  II.    APLYSOIDEA. 

Shell  much  reduced,  more  or  less  internal,  or  lost  altogether 
in  the  adult  state.  Head  with  two  pairs  of  tentacles.  Margins  of 
the  parapodia  separate  from  the  ventral  surface  of  the  foot,  and 
generally  modified  into  natatory  lobes.  Visceral  commissure 
usually  very  much  shortened,  except  in  Tethys.  Genital  duct 
monaulic,  the  hermaphroditic  duct  connected  with  the  penis  by 
a  ciliated  groove. 


Family  APLYSIIDAE. 

Animal  lengthened,  not  protected  by  a  shell,  the  neck  and 
head  narrower  than  the  body;  mouth  a  vertical  fissure;  anterior 
angles  of  the  head  produced  into  two  tentacular  lobes  folded 
above;  behind  them  the  cylindrical  or  conical  rhinophores,  slit 
above,  in  front  of  which  are  the  minute  eyes.  Parapodia  re- 
curved over  the  back,  forming  two  lateral  or  dorsal  lobes  en- 
closing the  mantle  and  ctenidium.  Genital  orifice  between  the 
dorsal  lobes,  communicating  by  a  long  furrow  with  the  evertible 
penis  which  is  near  the  anterior  right  tentacle.  Shell  nearly  or 
entirely  covered  by  the  mantle,  uncoiled,  in  the  form  of  a  con- 
cave plate,  sometimes  absent.  Mouth  with  corneous  jaws  and  a 
large,  multiserial  radula  composed  of  similar  teeth;  stomach 
armed  with  horny  nodules ;  anus  behind  the  branchial  plume. 

Subfamily  APLYSIINAE. 

Parapodial  lobes  well-developed,  their  anterior  ends  sep- 
arated ;  genital  orifice  in  front  of  the  branchia ;  radula  with  wide, 
denticulate,  rhachidian  teeth,  and  narrower,  serrate  and  denticu- 
late laterals.  Shell  flexible. 

Genus  TETHYS  Linne,  1758. 

Tethys,  Linne,  Systema  Naturae,  loth  ed.  1758,  p.  653. 
Laplysia,  Linne,  Systema  Naturae,  I2th  ed.  1767,  p.  1089. 
Aplysia,  Gmelin,  Systema  Naturae,  I3th  ed.  1788,  I,  VI,  p.  3103. 
Tethys,  Pilsbry,  Proc.  Acad.  Nat.  Sci.,  Philadelphia,  1895,  p.  347. 
Tethys,  Pilsbry,  Manual  of  Conchology,  Tryon,  XVI,  1896,  p.  65. 

Animal  swollen  behind,  narrower  in  front,  with  rather  long 
neck  and  head,  bearing  folded  tentacles  and  slit  rhinophores  as 
usual  in  the  family,  the  latter  about  midway  between  tentacles 
and  dorsal  slit.  Parapodia  arising  in  front  of  the  middle  of  the 
animal's  length,  ample,  freely  mobile,  free  throughout  their  length, 
or  united  for  a  distance  behind,  functional  as  swimming  lobes; 
anterior  ends  separated.  Mantle  nearly  covering  the  ctenidium, 
having  a  median  tube,  foramen,  or  orifice  communicating  with 
shell  cavity,  and  produced  behind  in  a  more  or  less  developed 


14  OPISTHOBRANCHIATA   OF   BRAZIL 

lobe  or  lobes,  rolled  to  form  an  excurrent  siphon.  Genital  orifice 
under  front  edge  of  mantle,  in  front  of  ctenidium ;  hypobranchial 
gland  present,  a  short  distance  behind  genital  opening.  Foot 
well  developed. 

Shell  very  thin,  membranaceous,  with  a  thin,  calcareous  inner 
layer,  nearly  as  large  as  mantle,  concave,  with  pointed,  small 
apex,  bearing  a  recurved  lamina,  and  having  a  concave,  posterior 
sinus. 

This  genus  is  usually  known  as  Aplysia,  an  etymological 
correction  by  Gmelin  of  the  name  Laplysia,  used  by  Linne  in  the 
1 2th  edition  of  the  Systema  Naturae.  As  pointed  out  by  Pilsbry, 
the  name  Tethys  is  unmistakably  applied  to  this  genus  by  Linne 
himself  in  the  loth  edition  in  1758,  and  hence  must  stand,  despite 
the  common  but  erroneus  usage. 

Two  species  of  this  genus  and  one  of  Notarchus  have  already 
been  recorded  from  the  coast  of  Brazil,  and  to  them  are  to  be 
added  the  following  two,  already  known  from  the  Antilles. 

Tethys   dactylomela    (Rang,   1828). 

PI.  I,  Figs.  1-7;  PI.  II,  Fig.  8;  PI.  Ill,  Figs.  9-14;  PI.  IX,  Fig.  38. 
Aplysia  dactylomela   Rang.     Histoire   Naturelle   des   Aplysiens, 

1828,  p.  56,  pi.  IX. 
Tethys   dactylomela    (Rang).      Pilsbry,    in    Tryon,    Manual    of 

Conchology,  XVI,  1896,  p.  75-76,  pi.  32,  figs,  16-19. 

"Length  about  17  cm.  Always  much  swollen  with  elongated 
head  and  tail ;  rugose.  Mantle  or  gill  cover  with  a  minute,  central 
tube  and  a  well  developed  siphon  behind.  Swimming  lobes  not 
united  as  far  forward  as  the  siphon. 

"Color  pale  yellow  of  various  shades,  more  or  less  covered  in 
different  individuals,  with  black  rings,  irregular  and  of  various 
sizes.  Inner  sides  of  lobes  and  the  mantle  with  large  black  spots 
of  different  forms.  Borders  of  the  swimming  lobes  tinged  with 
violet. 

"Shell  large,  much  dilated,  a  little  diaphanous,  amber  colored 
outside  with  a  visible  enamel  within;  posterior  sinus  deeply 
arcuate ;  beak  recurved,  triangular,  thick  and  calloused.  Altitude, 
forty-two  millimeters." 


TETHYS   DACTYLOMELA    (RANG) 


EXTERNAL  CHARACTERS. 

Six  specimens  of  this  widely  distributed  Antillean  species 
were  found  in  the  collection,  five  of  them  taken  from  the  same 
locality,  "Coral  reef,  Maceio,  Alagoas,  July  30,  1899,"  and  the 
sixth  from  "Pernambuco  stone  reef,  July  7,  1899,"  and  collected 
in  both  cases  by  A.  W.  Greeley.  No  further  notes  accompanied 
the  specimens,  but,  according  to  a  verbal  communication  from 
Mr.  Greeley,  the  preserved  material  was  of  nearly  the  same  col- 
oration as  in  life,  the  ground  color  being  slightly  deeper,  a  yel- 
lowish brown.  The  characteristic  ink  ejected  on  being  disturbed 
was  of  a  deep  purple  color.  Of  the  six  specimens  taken,  one  was 
quite  large,  being  over  twice  the  length  of  any  of  the  others, 
which  were  of  nearly  the  same  dimensions  throughout.  All  were 
in  a  good  state  of  preservation,  but  all  more  or  less  contracted, 
especially  in  the  region  of  the  mouth  and  head.  The  following 
table  gives  a  comparison  of  the  principal  dimensions. 


No. 

Length 

Width 

Height 

Length 
base  of 

parapodia 

Width 
space 
bet.  ant. 
ends  para- 
podia 

Width 
space 
bet.  post 

ends  para- 
podia 

Length 
of 
foot 

Width 
of 
foot 

1. 

140  mm. 

70mm. 

60  mm. 

97mm. 

18  mm. 

7  mm. 

135  mm. 

40mm. 

2. 

70    " 

40    " 

50    " 

55    " 

17    " 

18    " 

60    " 

18    " 

3. 
4 

65    " 

40    " 

40    " 

56    " 
56    " 

9    " 

3    " 
5    " 

63    " 

20    " 

5. 
6 

56    " 

20    " 

20    " 

34    " 

8    " 
8    " 

1.5" 
1  5" 

40    " 

18    " 

In  individual  No.  3  the  anterior  end  of  the  left  parapodium 
was  10  mm.  behind  that  of  the  right  side.  In  individuals  Nos.  4 
and  6  the  contraction  of  the  head  region  was  so  great  as  to 
invalidate  the  measurements  omitted  in  the  table  for  all  purposes 
of  comparison. 

Color.  The  general  plan  of  coloration  is  the  same  as  that 
given  in  the  revised  description  of  this  species  in  Tryon's  Manual 
of  Conchology,  Vol.  XVI,  p.  75,  and  quoted  above.  The  black 
rings  form  a  very  striking  color  characteristic,  their  centers  being 
free  from  pigment.  They  reach  a  diameter  in  the  largest  speci- 


l6  OPISTHOBRANCHIATA   OF   BRAZIL 

men  of  7.0  mm.,  the  band  of  pigment  itself  ranging  up  to  3.0 
mm.  in  width.  The  inner  surface  of  the  parapodial  lobes  bears 
several  branching  bands  of  black,  running  in  a  generally  vertical 
direction,  near  the  thin  margins,  with  occasional  isolated  blotches 
of  pigment  between  them,  and  below  merging  into  the  black  to 
greenish  black  area  at  the  bases  of  the  parapodia.  Between  the 
posterior  ends  of  the  parapodia  is  situated  a  median  longitudinal 
dark  band,  which  dilates  posteriorly  into  a  broad  crescentic  spot, 
the  points  of  which  are  prolonged  upward  for  a  short  distance 
along  the  inner  face  of  the  margins  of  the  parapodia.  The  dorsal 
surface  of  the  mantle  is  marked  with  irregular  blotches  of  black, 
tending  to  form  a  series  of  incomplete  rings.  The  under  surface 
of  the  mantle  is  yellowish  brown,  the  branchia  brownish  black, 
or  nearly  free  from  color. 

Parapodia.  The  parapodia  are  prominent  and  high,  their 
margins  thin.  The  posterior  half  of  the  mantle  is  rolled  into  an 
erect  tube,  the  siphon,  the  thin  crenulate  upper  margin  of  which, 
in  its  slightly  contracted  state  reaches  just  below  the  margins  of 
the  parapodia. 

Shell.  About  midway  of  the  length  of  the  mantle  in  the 
median  line  is  a  single  minute  opening,  borne  upon  a  well  marked, 
short  cylindrical  papilla,  communicating  with  the  shell  sac,  or 
mantle  cavity.  The  shell  is  of  good  size,  rather  convex,  very 
thin  and  translucent,  but  slightly  calcareous,  externally  very  pale 
yellow  in  color.  In  all  the  specimens  unfortunately  it  was  some- 
what broken,  the  inner  calcareous  surface  being  reduced  usually 
to  fragments.  The  thin  membranaceous  margin  of  the  shell  pro- 
jects beyond  the  calcified  portion  beneath,  its  anterior  and  right 
borders  are  rounded,  the  posterior  border  concave,  the  beak  much 
thickened,  triangular  and  recurved.  In  general  it  is  similar  to 
the  figures  of  Rang  for  the  species.  Length  23  mm.,  width  16 
mm.,  in  an  animal  of  70  mm.  total  body  length. 

Tentacles.  The  tentacles  and  head  region  generally  are 
more  or  less  contracted  in  all  the  specimens.  In  the  best  preserved 
ones  the  posterior  tentacles,  or  rhinophores  are  slender,  auriform, 
the  external  slit  being  carried  down  posteriorly  nearly  to  the  base 
of  the  organ. 

The  anterior  tentacles  are  much  broader,  stout,  auriform, 
triangular  in  general  outline,  their  outer  margins  being  con- 


TETHYS  DACTYLOMELA    (RANG)  17 

tinued  downward  to  the  mouth,  the  tips  auriculate,  their  posterior 
margins  forming  a  prominent  flap  closely  applied  to  the  anterior 
portion. 

Just  below  and  in  front  of  the  bases  of  the  rhinophores  the 
minute  black  eyes  shimmer  through  the  integument. 

Reproductive  opening.  The  male  genital  opening  lies  just 
below  the  base  of  the  right  anterior  tentacle,  a  strongly  defined 
groove  extending  backward  from  it  and  dorsally  between  the  para- 
podia  to  the  hermaphroditic  orifice  in  front  of  the  base  of  the 
branchia.  This  groove  is  marked  by  a  narrow  black  line  on  its 
right  margin  throughout  its  whole  length.  Behind  and  below 
the  genital  opening  is  a  large  conspicuous  circular  orifice,  the 
opening  of  the  hypobranchial  gland,  or  gland  of  Bohadsch. 

The  anal  opening  is  situated  upon  the  base  of  the  posterior 
wall  of  the  siphon,  presenting  a  pocket-like  appearance. 

The  renal  opening  is  small  and  slit  like,  1.2  mm.  in  length, 
and  lies  deep  in  the  mantle  cavity  above  the  posterior  end  of  the 
ctenidium,  some  distance  in  front  of  the  anus. 

Foot.  The  foot  is  broad  and  well  developed,  its  anterior  end 
rounded,  the  posterior  one  more  bluntly  pointed.  Its  margin  is 
clearly  defined  in  all  the  specimens,  its  well  developed  muscula- 
ture being  contracted,  giving  it  a  firm  rugose  texture,  in  contrast 
to  the  smooth  soft  surface  of  the  remainder  of  the  body. 

In  the  literature  scarcely  anything  is  to  be  found  upon  the 
internal  anatomy  of  this  species,  a  fact  too  frequently  true  of  the 
majority  of  the  members  of  this  family,  many  of  them  having 
been  described  by  the  shell  alone,  which,  as  Pilsbry  has  pointed 
out,  is  probably  the  least  characteristic  organ  of  the  animal.  The 
interrelations  of  this  widely  distributed  group  cannot  at  present 
even  be  approximated  on  account  of  this  lack.  With  a  view  to 
aiding  in  filling  up  this  gap  in  our  knowledge  I  have  made  detailed 
dissections  of  the  Aplysiidae  found  in  this  collection. 

INTERNAL  ANATOMY. 

In  the  description  of  the  internal  anatomy,  unless  otherwise 
stated,  all  of  the  measurements  given  are  taken  from  an  individ- 
ual of  70  mm.  total  length  in  the  well  preserved  alcoholic  specimen. 

The  body  wall  is  similar  to  that  of  other  members  of  the 
group,  the  external  integument  being  reinforced  by  interlacing 


1 8  OPISTHOBRANCHIATA  OF  BRAZIL 

bands  of  strong  muscle  fibres.  The  body  cavity  is  roomy,  and 
nearly  filled  by  the  viscera,  its  pseudo-peritoneum  being  colorless 
or  slightly  yellowish  in  hue. 

ALIMENTARY  SYSTEM. 

Pharyngeal  bulb.  The  mouth  communicates  by  a  very  short 
tube  with  the  pharyngeal  bulb,  a  strong,  muscular  organ  of  conical 
form.  Its  length  is  n.o  mm.  with  a  maximum  diameter  of  10.0 
mm.  Opened  from  above  the  deep,  rich  amber-colored  radula 
is  exposed,  and  in  front  of  it,  upon  each  side,  the  mandibular 
plates  of  a  similar  color.  The  latter  are  situated  at  the  anterior 
end  of  the  pharyngeal  bulb,  almost  completely  encircling  the  open- 
ing and  nearly  touching  each  other  above  and  below.  The  opales- 
cent lip  disc  is  elliptical  in  outline,  the  opening  appearing  as  a 
vertical  slit,  4.0  mm.  in  length,  while  immediately  within  it  the 
margins  of  the  mandibular  plates  are  seen.  These  plates  are 
roughly  rectangular  in  outline  (PI.  I,  fig.  7),  their  length  being 
5.5  mm.  and  their  breadth  3.0  mm.  The  posterior  margin  is 
bounded  by  a  sharp,  regularly  curved  line  of  opalescent  hue, 
while  the  anterior  margin  is  irregular,  and  more  or  less  jagged 
and  worn.  Each  plate  is  made  up  of  densely  packed  rodlets, 
nearly  straight,  or  slightly  bent,  and  of  approximately  the  same 
diameter  throughout  their  whole  length.  At  the  posterior  mar- 
gin of  the  plate  the  arrangement  of  these  rodlets  may  be  easily 
seen  (PI.  Ill,  fig.  12),  but  in  the  anterior  portion  such  an  arrange- 
ment cannot  be  made  out  clearly,  owing  to  the  overlapping  of 
the  rodlets  as  they  increase  in  length.  The  shorter  rodlets  are 
flattened  antero-posteriorly,  with  a  strong  tendency  to  the  forma- 
tion of  a  slight  concavity,  or  longitudinal  groove  upon  the  poste- 
rior face,  and  a  corresponding  convexity  in  front.  Their  average, 
greatest  width  is  0.005  mm-  Toward  the  anterior  border  the 
rodlets  increase  in  length,  their  basal  diameter  remaining  nearly 
the  same,  while  the  length  may  reach  0.124  mm.  The  outer 
extremity  is  bluntly  rounded,  the  distal  one-third  being  some- 
times slightly  enlarged,  or  club-shaped,  or,  in  other  cases,  entirely 
straight  throughout  (PI.  Ill,  fig.  13).  The  bending  and  dis- 
tortion, incident  to  microscopic  preparation  as  a  whole  mount, 
indicate  a  considerable  degree  of  flexibility. 

Radula.    The  radula  is  broad,  deeply  grooved  behind,  and  of 


TETHYS  DACTYLOMELA    (RANG)  IQ 

a  dark  amber  color.  As  is  usual  the  anterior  rows  of  teeth  are 
very  much  worn  and  broken,  so  that  even  their  number  is  un- 
certain. About  eleven  such  imperfect  rows  may  be  made  out, 
which  gradually  pass  over  into  forty-seven  complete  rows,  of 
which  the  last  twenty  are  still  inclosed  in  the  radula  sheath.  The 
total  number  of  rows  is  thus  about  fifty-eight.  The  greatest 
length  of  the  radula  is  9.0  mm.,  and  its  greatest  width  3.0  mm. 

The  number  of  teeth  varies  in  the  different  rows,  being 
quite  small  in  the  most  anterior  rows,  and  increasing  regularly 
in  the  succeeding  ones  to  26:1:26  in  the  twenty-fifth  row,  and 
38:1 : 38  in  the  fifty-fifth  one.  In  the  anterior  twenty  to  twenty- 
five  rows  the  teeth  are  much  worn,  scarcely  any  being  perfect, 
the  cusps  being  usually  blunted,  or  broken  entirely  away.  Typical 
teeth,  taken  at  intervals  across  the  radula  from  neighboring  rows, 
are  shown  in  figs.  I,  2  and  3,  of  PI.  I.  Fig.  I  represents  the 
median  and  first  lateral  teeth  of  the  49th  and  5oth  rows;  fig.  2 
shows  the  8th,  9th  and  loth  teeth  of  the  same  rows,  while  figs. 
3  and  4  give  the  i8th  to  2oth  of  the  5oth  row  and  the  32d  to  37th 
teeth  of  the  54th  row  respectively  all  under  the  same  magnifi- 
cation. The  rhachis  bears  a  single  large  tooth  in  each  row.  Its 
base  is  broad  and  trapezoidal  in  form,  the  broader  end  being 
directed  posteriorly.  It  varies  but  slightly  in  size  throughout 
the  length  of  the  radula,  averaging  0.216  mm.  in  the  diameter 
of  its  broader  posterior  end  and  0.06  mm.  in  the  diameter  of 
its  anterior  end,  with  a  length  of  0.156  mm.  In  the  anterior 
end  of  the  radula  the  base  is  often  divided  longitudinally,  or 
a  thinning  away  of  the  median  line  may  indicate  such  a  division 
as  incomplete.  The  posterior  margin  is  very  slightly  concave,  the 
anterior  one  deeply  emarginate,  the  notch  being  carried  up  on  the 
back  of  the  hook  as  a  deep  groove.  The  anterior  end  bears  a 
strong  hook,  which  is  as  broad  as  the  full  width  of  the  base  at 
its  anterior  end.  The  length  of  this  hook  averages  0.126  mm., 
seven-twelfths  the  length  of  the  base.  It  terminates  in  a  large 
median  blunt  cusp,  and  two  much  smaller  lateral  cusps.  The 
sides  of  the  median  cusp  bear  from  four  to  ten  thin  irregular 
denticles  on  either  side  in  the  posterior  portion  of  the  radula. 
These  denticles  are  either  separate  or,  more  usually,  united  at 
their  bases.  In  the  anterior  portion  these  denticles  are  either 
worn  away  or  undeveloped.  The  lateral  cusps  (PI.  I,  fig.  i),  are 


2O  OPISTHOBRANCHIATA  OF  BRAZIL 

one-fourth  to  one-half  the  length  of  the  median  one,  and,  in  the 
last  few  rows  may  bear  very  minute  serrulations,  chiefly  upon 
their  outer  margins. 

The  pleural  teeth  are  rather  uniform  in  outline,  the  inner- 
most and  outermost  being  slightly  smaller  than  the  remaining 
ones,  into  which  they  pass  in  a  graded  series.  The  general  form 
of  the  pleural  teeth  is  shown  in  PI.  I,  figs.  5  and  6,  in  dorsal  and 
lateral  view.  The  base  is  broadest  and  thickest  at  its  anterior 
end,  tapering  to  a  rounded  posterior  one  which  is  produced 
strongly  toward  the  outer  border  of  the  radula.  In  the  posterior 
portion  of  the  radula  the  base  is  broader  throughout  than  in  the 
anterior  region.  The  same  lateral  prolongation  is  shown  through- 
out the  whole  length  of  each  row,  being  most  strongly  marked 
about  the  middle  of  each  (PI.  I,  fig.  3).  The  anterior  end  of 
the  base  is  recurved  dorsally  in  a  strong,  broad  hook,  projecting 
upward  at  an  angle  of  about  45°  and  bearing  two  strong  unequal 
cusps,  which  are  about  as  broad  as  long  near  the  innermost  ends 
of  the  row,  and  increase  in  length  progressively  until  they  become 
about  two  and  one-half  times  as  long  as  broad,  a  proportion 
reached  by  the  tenth  tooth  (PI.  I,  figs.  I,  2).  The  smaller 
external  cusp  measures  one-half  to  one-third  the  length  of  the 
larger,  and  is  of  the  same  general  form.  Both  cusps  bear 
typically  a  varying  number  of  well  marked  irregular  denticles 
upon  their  margins,  which  may  be  entirely  separate,  or,  as  is 
usually  the  case,  are  united  at  their  bases  into  a  thin  marginal 
band.  These  denticles  may  be  fairly  uniform  in  size  and  shape 
(PI.  I,  fig.  2,  10),  or  more  often,  very  irregular  (PI.  I,  figs. 
2,  3).  The  small  external  cusp  bears  a  lesser  number  of  denticles, 
which  may  be  few  and  small,  or  large  and  irregular,  often  at- 
taining such  a  size  as  to  give  the  cusp  the  appearance  of  being 
divided  (PI.  I,  fig.  3).  The  dimensions  of  a  typical  large 
pleural  tooth  are:  length  of  base,  0.288  mm.,  greatest  width  of 
base,  0.108  mm.,  length  of  larger  cusp,  0.102  mm.,  length  of 
smaller  cusp  0.042  mm.  The  external  pleurae  decrease  pro- 
gressively in  size  outwards,  the  outermost  two  or  three  in  many 
cases  being  reduced  to  the  base  alone,  the  recurved  hooks  being 
undeveloped  (PI.  I,  fig.  4). 

Dobson  in  the  Journal  of  the  Linnaean  Society  (XV,  1880, 
P-  I59)>  figures  several  teeth  from  Tethys  dactylomela  which  agree 


TETHYS  DACTYLOMELA    (RANG)  21 

in  general  with  those  here  given.  Eliot,  in  his  "Notes  on  Tecti- 
branchs  and  Naked  Mollusks  from  Samoa,"  Proc.  Philadelphia 
Academy,  1899,  p.  515,  states  that  the  radula  of  a  Tethys  dacty- 
lomela  examined  by  him  possessed  a  unicuspid  central  tooth,  the 
laterals  having  an  inner,  but  no  outer  cusp,  a  condition  decidedly 
different  from  that  described  above  in  the  specimens  which  I  have 
examined. 

Salivary  glands.  The  ducts  of  the  salivary  glands  emerge 
from  the  buccal  mass  on  its  posterior  surface  on  either  side  of  the 
anterior  end  of  the  esophagus.  The  glands  are  long  flattened 
strap-shaped  structures,  1.5  mm.  in  greatest  width.  They  pass 
through  the  esophageal  collar  formed  by  the  central  nervous 
system,  extend  backward  along  the  left  side  of  the  visceral  mass, 
the  left  one  above,  and  dwindle  away  posteriorly,  their  tips  be- 
ing attached  to  the  sides  of  the  anterior  portion  of  the  first 
triturating  stomach,  the  tip  of  the  left  one  being  situated  dorsally, 
that  of  the  right  one  ventrally. 

Esophagus  and  stomach.  The  esophagus  is  a  short  broad 
thin-walled  tube  about  6.5  mm.  in  length,  dilating  posteriorly 
into  the  capacious  stomach.  Its  inner  surface  is  smooth,  save  for 
a  few  low  longitudinal  ridges.  In  the  stomach  may  be  dis- 
tinguished three  divisions.  The  first,  or  ingluvies,  is  everywhere 
very  thin  walled,  its  inner  surface  is  smooth  and  passes  gradually 
into  that  of  the  esophagus  in  front.  In  all  the  specimens  exam- 
ined the  ingluvies  was  greatly  distended  with  fragments  of  algae. 
In  its  lower  posterior  portion  the  ingluvies  suddenly  constricts 
into  the  "first  triturating  stomach"  of  Mazzarelli,  clearly  marked 
externally  by  its  strong  muscular  wall,  the  fibres  of  which  are 
mainly  arranged  in  a  circular  direction.  The  width  of  this  band 
varies  from  n.o  mm.  to  18.0  mm.  in  the  specimens  examined, 
the  diameter  of  the  contracted  stomach  at  this  point  ranging  from 
15.0  mm.  to  20.0  mm.  Borne  upon  the  inner  surface  of  this  wall 
is  a  series  of  strong  horny  pyramidal  teeth  of  a  light  amber 
color.  The  sides  of  these  teeth  are  formed  by  four  roughly 
triangular  faces,  and,  the  two  anterior  ones  being  larger  than 
the  two  posterior  ones,  the  tip  of  the  tooth  is,  in  consequence, 
inclined  backward.  The  teeth  are  borne  upon  plate-like  eleva- 
tions of  the  epithelium,  corresponding  in  shape  to  the  bases  of 
the  teeth.  In  alcoholic  material  the  teeth  are  readily  separable 


22  OPISTHOBRANCHIATA   OF   BRAZIL 

from  these  elevations.  The  largest  one  of  the  basal  impressions 
thus  left  measured  6.0  mm.  in  length  by  5.0  mm.  in  width.  The 
teeth  are  arranged  in  a  sort  of  quincunx  in  about  six  transverse 
rows,  the  larger  ones  occupying  the  middle  and  posterior  por- 
tion, and  in  front  of  these  the  smaller  ones  are  alternately  ar- 
ranged. The  largest  of  these  teeth  measured  4.0  mm.  in  height. 
In  the  contracted  state  of  this  portion  of  the  stomach,  the  apices 
of  these  teeth  meet  in  the  center  of  the  lumen  and  fit  closely 
together,  thus  nearly  closing  the  opening. 

Succeeding  this  first  triturating  stomach  is  a  somewhat 
wider  and  longer,  much  thinner  walled  division  of  the  alimentary 
canal,  the  "second  triturating  stomach"  of  Mazzarelli.  Its  walls 
are  much  less  muscular  than  those  of  the  first  stomach,  being  of 
practically  the  same  thickness  as  those  of  the  ingluvies.  Instead 
of  bearing  numerous  small  teeth  as  in  those  Mediterranean 
species  studied  by  Mazzarelli  ('93),  the  teeth  are  reduced  to  a 
single  series  arranged  in  a  transverse  row,  about  midway  of  the 
length  of  the  organ.  These  teeth  are  very  small  and  readily 
dehiscent;  their  basal  impressions  are  nearly  round  in  outline, 
and  about  0.7  mm.  in  diameter.  There  are  seven  such  impressions 
in  the  first  specimen  dissected,  six  and  eight  in  others,  arranged  in 
a  transverse  row,  and  occupying  about  one-half  of  the  total  cir- 
cumference of  the  whole  organ.  The  remainder  of  the  lining  of 
the  second  stomach  is  entirely  smooth. 

Posterior  visceral  complex.  The  hinder  portion  of  the  second 
stomach  is  situated  between  the  two  anterior  lobes  of  the  large 
liver,  thence  passing  rather  abruptly  into  the  intestine.  The  poste- 
rior visceral  mass  is  made  up  of  the  liver,  the  intestine  and  the 
hermaphroditic  gland,  and  is  broadly  conical  in  general  form, 
the  apex  being  directed  posteriorly,  and  the  elliptical  base  lying 
against  the  posterior  part  of  the  stomach  and  partially  inclosing 
it.  It  is  covered  by  a  delicate  membrane  of  connective  tissue, 
the  peritoneal  lining  of  the  pseudo-coelom.  The  intestine  is  very 
thin  walled,  and  is  filled  with  finely  divided  detritus  of  algal 
nature.  It  describes  a  series  of  complicated  loops  upon  the  liver, 
in  the  surface  of  which  it  is  imbedded.  The  intestine  enters  the 
liver  at  its  lower  border,  passes  backward,  thence  upward  and 
forward  describing  a  long  loop  upon  the  upper  surface  of  the 
liver  toward  its  right  side,  to  return  again  to  the  left,  from  which 


TETHYS  DACTYLOMELA    (RANG)  23 

it  passes  in  a  sinuous  course  to  the  anus,  situated  upon  the  poste- 
rior wall  of  the  siphon.  At  the  beginning  of  the  intestine  its 
dilated  lumen  receives  two  large  biliary  ducts,  which  ramify 
throughout  the  substance  of  the  liver.  Two  low  ridges,  bounding 
a  shallow  groove,  lie  along  the  intestinal  wall  in  contact  with  the 
liver,  near  the  beginning  of  the  tube.  These  may  be  followed 
backward  into  a  long  curved  blind  tube,  in  the  wall  of  which  they 
become  overlapping  elevations,  dividing  it  into  two  longitudinal 
chambers  which  are  in  communication  at  the  end  of  the  tube. 
This,  the  hepatic  coecum,  is  imbedded  in  the  substance  of  the 
liver  throughout  nearly  its  whole  length,  but  its  blind  termination 
reappears  at  the  surface  as  a  small  rounded  area,  which  might 
readily  be  mistaken  for  a  portion  of  the  wall  of  the  intestine. 
The  coecum  describes  a  C  shaped  loop  of  nearly  10.0  mm.  in 
length  with  a  fairly  constant  diameter  of  1.5  mm. 

CENTRAL  NERVOUS  SYSTEM. 

The  ganglia.  The  central  nervous  system  of  Tethys  dacty- 
lomela  (PL  II,  fig.  8)  is  made  up  of  eight  paired  ganglia  grouped 
around  the  anterior  end  of  the  esophagus,  close  to  its  origin  from 
the  pharyngeal  bulb.  These  are  the  cerebral,  the  pleural,  the 
pedal  and  the  buccal  ganglia,  the  right  and  left  components  of 
each  pair  being  united  by  commissures,  while  the  ganglia  of  each 
side  are  united  by  the  cerebro-pedal,  the  cerebro-pleural,  the 
cerebro-buccal  and  the  pleuro-pedal  connectives.  In  addition  to 
these  centrally  located  ganglia,  there  are  others,  more  or  less 
distant  from  the  central  system.  Chief  of  these  are  the  parieto- 
visceral,  the  genital,  and  the  ganglia  of  the  anterior  and  the  poste- 
rior tentacles.  The  central  nervous  system  is  closely  enveloped 
by  a  capsule  of  connective  tissue  in  a  firm  sheath,  which  renders 
the  dissection  of  the  nerves  a  matter  of  some  difficulty.  The 
ganglia,  their  commissures,  connectives  and  nerves  will  be  taken 
up  in  order  in  the  following  description.  The  figures  and  de- 
scriptions given  by  Von  Ihering  ('77),  Mazzarelli  ('93),  and 
Vayssiere  ('85),  based  upon  European  species  of  Tethys,  vary 
so  much  from  the  results  which  I  have  obtained  in  Tethys  dacty- 
lomela  and  in  T.  cervina  that  considerable  detail  seems  to  be  justi- 
fied in  the  following  account.  In  fig.  8  of  PI.  II  I  have  endeavored 
to  give  an  accurate  representation  of  the  central  nervous  system 


24  OPISTHOBRANCHIATA   OF   BRAZIL 

of  this  species  in  dorsal  view,  the  abbreviations  in  the  following 
description  all  referring  to  this  figure.  The  nerves  are  numbered 
rather  arbitrarily  in  the  order  of  their  origin  from  the  ganglia, 
from  above  and  in  front,  downward  and  backward,  the  relative 
peripheral  distribution  not  being  primarily  considered  in  this 
arrangement. 

Cerebral  Nerves.  The  cerebral  ganglia  (cer.  g.}  are  situated 
upon  the  dorsal  side  of  the  esophagus  at  its  anterior  end,  and  are 
so  closely  applied  to  each  other  that  the  cerebral  commissures 
connecting  them  are  very  short,  the  two  ganglia  being  practically 
fused  together  in  the  median  line  into  a  single  mass.  They  are 
rounded,  and  flattened  upon  their  dorsal  surface,  and  fit  closely 
down  upon  the  underlying  esophagus.  From  the  sides  of  the 
ganglia,  close  up  to  the  origin  of  the  fifth  nerves,  arise  the  strong 
cerebro-buccal  connectives,  (c.  b.  con.},  which  curve  downward, 
around  the  esophagus,  to  the  buccal  ganglia.  Below  and  behind 
the  origin  of  these  arise  the  cerebro-pedal  connectives,  (c.  p.  con.}, 
which  pass  downward  and  outward  to  the  large  pedal  ganglia, 
(ped.  g.},  beneath  the  esophagus,  and,  close  to  the  origin  of  the 
latter  pair,  the  equally  stout  cerebro-pleural  connectives  (c.  pi. 
con.}  are  given  off.  These  pass  downward,  outward  and  back- 
ward, and  terminate  in  the  small  pleural  ganglia  (/>/.  g.},  resting 
upon  the  upper  border  of  the  pedal  ganglia. 

From  the  cerebral  ganglia  arise  six  pairs  of  nerves,  the 
origin  and  distribution  of  which  is  the  same  for  both  sides,  unless 
otherwise  noted  in  the  following  description. 

The  first  nerve  (ci}  is  a  strong  one,  arising  from  the  anterior 
border  of  the  ganglion,  passing  forward  over  the  pharyngeal 
bulb,  and  is  distributed  to  the  skin  and  muscles  in  the  region  of  the 
mouth. 

The  second  nerve  (cz},  is  broad  and  strong,  arising  imme- 
diately behind  the  first.  After  a  short  course  it  bifurcates,  its 
more  slender  external  division  passing  to  the  anterior  tentacle, 
and  terminating  in  a  small  ganglion  at  its  distal  extremity.  The 
stout  inner  branch  splits  up  into  a  number  of  smaller  branches, 
all  terminating  in  the  integument  in  the  neighborhood  of  the 
mouth. 

The  third  nerve  (cj),  arises  immediately  behind  the  first, 
but  more  dorsally.  It  is  more  slender,  and  passes  to  the  rhino- 


TETHYS   DACTYLOMELA    (RANG)  2  5 

phore,  giving  off  a  few  delicate  branches  to  the  integument  near 
its  base,  and  terminating  in  a  small  ganglion  at  its  distal  extremity. 

The  fourth,  or  optic  nerve  (£4),  is  very  slender  and  quite 
long.  It  arises  immediately  behind  and  exterior  to  the  third, 
and  is  inclosed  in  a  common  sheath  of  connective  tissue  with  it 
for  a  very  short  distance,  much  less  than  that  described  by  Maz- 
zarelli  for  the  Mediterranean  species.  It  is  unbranched,  and 
passes  directly  to  the  eye.  No  trace  of  an  optic  ganglion  can  be 
made  out  at  its  base  with  the  dissecting  microscope,  though  sec- 
tions might  show  its  presence. 

The  fifth  nerve  (^5),  arises  from  the  lateral  border,  imme- 
diately in  front  of  the  cerebro-buccal  connectives  and  is  rather 
slender.  On  the  left  side  it  courses  forward  and  is  distributed 
to  the  body  wall  in  the  region  of  the  mouth.  Its  fellow  of  the 
right  side  passes  forward,  and  divides  into  two  branches,  one  of 
which  is  soon  lost  among  the  muscles  of  the  body  wall,  imme- 
diately below  the  anterior  portion  of  the  penis.  The  second, 
more  slender  branch  courses  forward,  parallel  to  the  penis,  giving 
off  three  branches  at  intervals,  which  pass  to  the  latter  organ,  the 
main  nerve  being  finally  distributed  to  the  muscles  of  the  mouth 
region. 

The  sixth  pair  form  the  acoustic  nerves.  They  are  included 
in  the  cerebro-pedal  connectives  for  about  one-half  of  their  length, 
and  then  become  separate  from  them  as  very  delicate  nerves, 
passing  directly  to  the  otocysts,  rounded  capsules  lying  close  to 
the  bases  of  the  cerebro-pedal  connectives  upon  each  side.  These 
nerves  are  not  shown  on  PI.  II. 

Pedal  ganglia.  The  pedal  ganglia  (ped.  g.),  are  the  largest 
of  the  central  nervous  system,  3.0  mm.  in  greatest  diameter, 
approximately  circular  in  general  outline,  flattened  upon  the 
antero-ventral  surface  and  strongly  arched  upon  the  postero- 
dorsal  face,  thus  having  a  nearly  hemispherical  form.  They  are 
united  below  the  esophagus  by  a  stout,  transverse  commissure, 
(p.  com.),  3.0  mm.  in  length,  and  i.o  mm.  in  diameter.  This  is 
inclosed  within  a  broad,  flattened  sheath  of  connective  tissue, 
which  also  contains  near  its  upper  anterior  margin  a  very  delicate 
subcerebral  commissure,  connecting  the  cerebral  ganglia  together 
below  the  esophagus.  This  latter  commissure  is  so  fine  that  it 
is  made  out  with  certainty  only  in  transverse,  serial  sections  of 


26  OPISTHOBRANCHIATA   OF   BRAZIL 

the  whole  band.  From  the  ventro-posterior  margin  of  each  pedal 
ganglion  a  much  more  slender  parapedal  commissure  (p.  p.  com.) 
arises.  It  is  7.0  mm.  in  length,  being  more  than  double  that  of  the 
thicker  pedal  commissure,  and  describes  a  posteriorly  directed 
loop  below  the  esophagus.  Somewhat  to  the  left  of  its  middle 
point  a  long  slender  unpaired  nerve  (a)  is  given  off,  in  one  case 
being  formed  by  a  union  of  a  short  branch  from  each  side  of  the 
loop,  in  others  coming  from  the  left  side  alone.  It  passes  back- 
ward and  is  distributed  to  the  pedal  artery  and  foot. 

From  the  pedal  ganglia  arise  ten  pairs  of  nerves,  which  show 
such  differences  in  the  two  sides  that  they  are  here  described 
separately. 

Left  pedal  nerves.  The  first  nerve  (p.i),  is  quite  slender. 
It  arises  from  the  upper  outer  border  of  the  ganglion  and  passes 
backward  and  is  distributed  to  the  peritoneum  and  muscles  of  the 
posterior  dorsum. 

The  second  nerve  (p. 2},  arises  close  below  the  first  and  is 
of  similar  size.  It  bifurcates  close  to  the  ganglion,  one  of  the 
rami  thus  formed  passing  backward  to  a  similar  distribution 
as  that  of  the  first  nerve ;  the  other  ramus  divides  into  (a)  a  branch 
curving  forward  and  forming  an  anastomosis  with  a  branch  of 
the  second  pleural  nerve,  described  below,  and  (&)  a  second 
branch  which  is  distributed  to  the  muscles  of  the  dorso-lateral 
region. 

The  third  (p. 3),  is  a  rather  slender  nerve  arising  just  below 
the  first  and  second,  and  more  upon  the  anterior  face  of  the  gan- 
glion. In  one  instance  it  appeared  as  two  nerves  very  close 
together.  It  branches  to  the  integument  and  muscles  of  the  dorsal 
wall  above  the  pharyngeal  bulb,  one  branch  passing  undivided  to 
the  region  of  the  eye. 

The  fourth  nerve  (p. 4),  arises  from  the  lateral  margin  of 
the  ganglion,  is  rather  long  and  strong,  passing  backward  to  its 
distribution  in  the  anterior  portion  of  the  parapodium. 

The  fifth  (p. 5),  is  a  strong  nerve  from  the  mid-lateral  margin 
of  the  ganglion.  It  soon  divides  into  three  branches,  the  anterior 
one  of  which  passes  to  the  muscles  of  the  body  wall,  the  other 
two  to  the  parapodium. 

The  sixth  nerve  (p. 6},  is  the  largest  of  the  pedal  group.  It 
arises  close  to  the  root  of  the  fifth,  and  from  its  distribution  is 


TETHYS  DACTYLOMELA    (RANG)  2.J 

termed  the  posterior  pedal  nerve.  It  soon  divides  into  two  main 
branches  of  unequal  size,  which  pass  backward  and  ramify  to 
the  posterior  portion  of  the  foot,  giving  off  a  few  slender  branches 
to  the  mid-lateral  region  of  the  same. 

From  the  ventro-anterior  face  of  the  ganglion,  near  the 
entrance  of  the  cerebro-pedal  connectives  arises  a  very  slender 
nerve,  the  seventh  (/>./).  A  short  distance  below  it,  and  from  the 
same  face,  the  ninth  nerve  (p. 9),  is  also  given  off.  These  two 
nerves  are  closely  enmeshed  in  the  capsule  of  connective  tissue 
enveloping  the  posterior  end  of  the  pharyngeal  bulb,  and  may  be 
easily  overlooked.  A  short  distance  from  their  origin  they  are 
connected  by  an  anastomosis,  and  beyond  this  the  two  have  a 
similar  distribution,  branching  richly  to  the  peritoneum,  the  aorta, 
and  the  muscles  of  the  dorso-lateral  wall  of  the  body. 

The  eighth,  or  median  pedal  nerve,  (p. ,8),  arises  at  the  outer 
lower  margin  of  the  ganglion,  passes  outward  and  backward, 
dividing  into  two  nearly  equal  rami,  which  are  distributed  to  the 
median  region  of  the  foot. 

The  tenth,  or  anterior  pedal  nerve  (/>.io),  is  the  lowermost 
one  of  the  series.  It  is  of  about  equal  caliber  to  the  eighth,  and 
divides  into  three  main  branches  which  curve  forward  to  the 
anterior  portion  of  the  foot. 

Right  pedal  nerves.  The  first  pedal  nerve  (p.i},  arises  as 
a  slender  process  from  the  outer  upper  margin  of  the  ganglion, 
and  soon  divides  into  two  unequal  branches.  The  larger  of  these 
passes  directly  to  the  muscles  of  the  lateral  wall.  The  other 
branch  subdivides  again,  in  a  short  distance,  into  an  anterior  and 
a  posterior  branch.  The  posterior  one  of  these  innervates  the 
penis,  the  anterior  one  runs  parallel  to  the  latter  organ,  gives  oil 
two  or  more  delicate  twigs  to  it,  which  anastomose  with  the  sub- 
divisions of  the  posterior  branch,  the  main  trunk  terminating  in 
the  muscles  of  the  mouth  region  on  the  right  side. 

The  second  and  third  nerves  are  closely  associated  at  their 
origin,  some  individuals  showing  them  as  separate  nerves,  while 
others  show  the  two  united  as  a  single  nerve  for  a  very  short 
distance.  In  fig.  8  of  PI.  II  I  have  shown  the  separate  condition. 
In  Tethys  cervina,  as  will  be  seen,  the  united  condition  was 
found,  and  further  comment  will  be  made  in  the  description  of 
the  central  nervous  system  of  that  form. 


28  OPISTHOBRANCHIATA   OF   BRAZIL 

The  second  nerve  (/>.<?),  arises  slightly  in  front  of  and  below 
the  third,  in  the  instance  figured  on  the  plate,  passes  outward 
and  gives  off  a  branch  which  forms  an  anastomosis  with  the  nerve 
from  the  right  pleural  ganglion  described  below.  The  main 
branch  passes  to  the  lateral  retractor  muscle  of  the  head,  a  slender 
branch  also  being  distributed  to  the  dorso-lateral  wall. 

The  third  nerve  (p. 5),  is  usually  stronger,  and  is  much 
longer,  coursing  backward.  It  sends  one  branch  to  the  muscles 
of  the  dorsum,  another  farther  on  to  the  muscles  and  integument 
of  the  side,  a  third  to  the  Organ  of  Bohadsch,  or  hypobranchial 
gland,  and,  after  giving  off  one  or  two  branches  to  the  muscles  of 
the  body  wall,  finally  terminates  in  the  right  parietal  ganglion, 
thus  forming  a  pedo-parietal  connective.  The  branch  given  off 
to  the  Organ  of  Bohadsch  also  forms  an  anastomosis  with  a  re- 
current branch  from  the  second  nerve  of  the  left  visceral  gan- 
glion, to  be  described  farther  on. 

The  fourth  (p. 4),  is  a  moderate  nerve  in  diameter  but  quite 
long.  It  arises  from  the  right  margin  of  the  ganglion,  courses 
backward,  and  is  distributed  to  the  right  parapodium,  like  its 
fellow  of  the  opposite  side. 

The  fifth  nerve  (p. 5),  arises  close  in  front  of  the  root  of  the 
sixth  from  the  median  margin  of  the  ganglion.  Its  strong  trunk 
soon  splits  into  three  nearly  equal  subdivisions,  the  most  anterior 
one  of  which  is  distributed  to  the  body  wall  in  front  of  the  para- 
podium,  the  remaining  two  ramifying  in  the  parapodium  itself. 

The  sixth,  or  posterior  pedal  nerve,  (p. 6),  is,  as  on  the  left 
side,  one  of  the  largest  nerves  from  the  ganglion.  Its  origin  and 
relations  are  similar  to  those  of  its  fellow,  which  is  also  true  of 
the  eighth  (p.8)  and  tenth  (p.io),  the  median  and  anterior  pedal 
nerves  respectively.  In  the  last  named  there  is  a  slight  tendency 
to  variation  in  the  number  of  the  main  branches  close  to  the 
ganglion,  but  otherwise  these  nerves  present  no  great  differences 
on  the  two  sides,  nor  in  different  individuals. 

Close  to  the  root  of  the  eighth  nerve  and  a  little  behind  it, 
on  the  outer,  posterior  face  of  the  ganglion  is  found  the  origin 
of  the  parapedal  commissure  (p.  p.  com.).  Upon  the  left  side 
this  commissure  originates  from  the  inner  ventral  margin  of  the 
ganglion. 

The  seventh  (/>./),  and  ninth  (>.p),  nerves,  like  the  cor- 


TETHYS  DACTYLOMELA    (RANG)  2Q 

responding  nerves  of  the  left  side,  arise  from  the  ventro-anterior 
face  of  the  ganglion,  and  present  some  difficulty  as  to  their  exact 
numerical  order  with  respect  to  the  other  nerves  of  the  same  gan- 
glion. They  are  also  closely  bound  up  in  the  connective  tissue 
sheath  surrounding  the  end  of  the  pharyngeal  bulb.  The  seventh 
nerve  is  slightly  larger  than  the  ninth,  and  is  distributed  mainly 
to  the  penis,  and  the  body  wall  in  the  immediate  neighborhood  of 
that  organ.  It  also  forms  a  strong  anastomosis  with  a  branch 
of  the  ninth,  as  is  shown  in  the  fig.  8  of  PI.  II.  The  ninth  nerve 
is  distributed  mainly  to  the  muscles  of  the  body  wall  below  the 
lateral  retractor  of  the  head. 

Pleural  ganglia.  The  pleural  ganglia  {pi.  g),  the  "proto- 
visceral  ganglia"  of  Mazzarelli  ('93),  are  quite  small,  i.o  mm. 
in  diameter,  and  nearly  spherical.  They  are  situated  upon  the 
upper  posterior  face  of  the  pedal  ganglia,  and  are  connected 
with  them  by  the  extremely  short  pleuro-pedal  connectives.  From 
the  posterior  surface  of  the  left  pleural  ganglion  arises  the  long 
and  strong  pleuro-visceral  connective  (pi.  v.  con.),  while  from  a 
nearly  similar  position  upon  the  pleural  ganglion  of  the  right 
side  is  given  off  the  pleuro-parietal  connective  (pi.  par.  con.), 
nearly  equal  in  length.  These  two  connectives  pass  directly  back- 
ward, converging  to  terminate  in  a  pair  of  ganglia,  the  parieto- 
visceral  ganglia,  lying  on  the  inner  surface  of  the  dorsal  body 
wall  at  a  point  midway  between  the  anterior  bases  of  the  pleuro- 
podia  and  close  to  the  anterior  insertion  of  the  mantle. 

The  pleural  ganglia  are  usually  described,  e.  g.  by  Mazza- 
relli ('93,  p.  108),  as  not  giving  off  any  nerves  in  the  Aplysiidae. 
But  in  Aplysiella  petalifera  Rang  Pelseneer  ('94)  describes  a 
lateral  nerve  arising  from  each  pleural  ganglion  and  forming  an 
anastomosis  with  a  pedal  nerve  of  the  same  side,  which  condition, 
he  further  states,  also  exists  in  certain  species  of  Aplysia  and  the 
Gymnosomata.  Vayssiere  ('85)  describes  and  figures  a  nerve 
from  each  lateral  visceral  (pleural)  ganglion  in  Notarchus 
punctatus  Philippi,  which  is  associated  in  a  part  of  its  course 
with  a  pedal  nerve  to  the  mantle,  and  is  distributed  to  the  lateral 
tissues  of  the  body  on  the  right  side,  at  the  base  of  the  branchia. 
Whether  an  anastomosis  of  these  two  nerves  occurs  or  not  does 
not  appear  from  his  description.  In  the  two  species  of  Aplysiidae 
from  Brazil  unmistakable  though  slender  nerves  do  arise  from  the 


30  OPISTHOBRANCHIATA   OF   BRAZIL 

pleural  ganglia,  and  equally  unmistakable  anastomoses  occur 
with  a  pedal  nerve  in  each  case.  These  relations  will  be  taken 
up  in  their  order. 

Left  pleural  nerves.  From  the  outer  upper  margin  of  the 
left  pleural  ganglion  arise  two  nerves  (pi.  I,  pi.  2}  close  together, 
and  are  closely  enmeshed  in  the  capsule  of  dense  connective  tissue 
surrounding  the  central  nervous  system.  They  are  both  dis- 
tributed to  the  muscles  of  the  lateral  and  dorsal  body  wall  in  the 
immediate  vicinity  of  the  ganglion.  The  second  of  these  nerves 
is  connected  by  an  anastomosing  branch  with  the  second  pedal 
nerve  of  the  same  side  as  is  seen  in  the  figure. 

Right  pleural  nerves.  From  the  right  pleural  ganglion  a 
single,  fair  sized  nerve  arises  (pi.  i)  below  and  in  front  of  the 
origin  of  the  pleuro-parietal  connective.  It  passes  outward  and 
forms  an  anastomosis  with  a  branch  of  the  second  pedal  nerve 
(p.2)  of  the  right  side.  The  double  trunk  thus  formed  then 
breaks  up  into  a  number  of  branches  in  the  peritoneal  membranes 
and  in  the  dorso-lateral  wall  of  the  body. 

Buccal  ganglia.  The  buccal  ganglia  (hue.  g)  are  nearly 
vertically  placed  upon  the  posterior  face  of  the  pharyngeal  bulb 
just  below  the  beginning  of  the  esophagus  (PI.  Ill,  fig.  9)  and 
present  an  anterior  slightly  concave  face  in  contact  with  the 
bulb,  and  a  posterior  arched  one,  turned  away  from  it.  These 
ganglia  are  plump  rounded  bodies  of  an  elliptical  outline,  slightly 
flattened,  and  closely  united  in  the  median  line  by  a  broad  and 
very  short  commissure.  On  Plate  II  the  buccal  ganglia  are  shown 
in  their  relations  with  the  remainder  of  the  central  nervous 
system;  in  figures  10  and  n  of  Plate  III  they  are  shown  isolated 
in  ventro-posterior  and  dorso-anterior  views  respectively.  The 
short  strong  cerebro-buccal  connectives  (c.  b.  con.)  unite  them 
to  the  cerebral  ganglia  above,  being  inserted  laterally  upon  the 
posterior  surface,  between  the  bases  of  the  second  and  third 
buccal  nerves  (PI.  Ill,  figs.  9,  10  and  n),  and  curving  laterally 
upward  to  the  cerebral  ganglia.  All  the  nerves  of  the  buccal 
ganglia  bear  small  white  pigment  spots  arranged  in  a  single 
series  at  regular  intervals  along  their  proximal  portions. 

Buccal  nerves.  In  the  description  following  the  numbering 
of  the  nerves  follows  their  order  of  origin  from  the  anterior  end 
of  the  ganglia  backward,  an  order  followed  by  Mazzarelli  on  p. 


TETHYS   DACTYLOMELA    (RANG)  3! 

107  of  his  Monografia,  but  the  notation  of  his  fig.  9,  tav.  IV  does 
not  follow  the  same,  nor  is  there  any  reference  made  to  the  figure 
in  the  description. 

The  first  nerve  is  a  strong,  unpaired,  median  one  arising 
upon  the  dorsal,  median  region  of  the  group  by  the  union  of  a 
large  bundle  of  fibres  from  each  ganglion  (PI.  Ill,  fig.  n,  /).  It 
almost  immediately  bifurcates  into  two  equal  subdivisions  which 
pass  directly  into  the  pharyngeal  bulb,  and  are  distributed  to  the 
muscles  of  the  rotella,  bearing  the  radula. 

The  second  nerve  (PI.  Ill,  figs.  9,  10,  n,  2},  arises  antero- 
laterally  and  courses  around  the  external  face  of  the  pharyngeal 
bulb  to  the  attachment  of  the  lateral  M.  retractor  bulbi.  Here 
it  divides  into  two  branches,  the  posterior  one  passing  directly 
inward,  ramifies  among  the  deep  muscles  of  the  radula,  while 
the  anterior  branch  courses  forward  and  is  distributed  to  the  M. 
ant.  lateralis  bulbi,  and  to  the  deeper  muscles  of  the  bulb. 

The  third  nerve  (PI.  Ill,  figs.  9,  10,  n,  j),  arises  close  above 
the  base  of  the  second  nerve  and  passes  around  the  side  of  the 
bulb  above  and  diverging  slightly  from  it.  At  the  posterior 
border  of  the  M.  antero-lateralis  bulbi  it  forks  and  passes  beneath 
that  muscle,  giving  off  branches  to  it  as  it  passes  deeper  into  the 
bulb.  It  may  be  traced  forward  to  the  anterior  end  of  the 
bulb,  where  its  delicate  branches  are  finally  lost  among  the  deeper, 
circular  muscle  fibres. 

The  fourth  nerve  (PI.  Ill,  figs.  9,  10,  n,  4}  arises  from  the 
lateral  margin  of  the  ganglion,  behind  and  above  the  origin  of 
the  third,  and  passes  upward  over  the  postero-dorsal  face  of  the 
pharyngeal  bulb,  following  closely  the  external  border  of  the 
proximal  portion  of  the  salivary  gland  to  the  appearance  of  its 
duct  at  the  surface  of  the  bulb.  Near  this  point  it  penetrates 
the  outer  layers  of  the  muscular  wall,  and  passes  forward  in  it  to 
the  anterior  end  of  the  bulb,  giving  off  numerous  branches  to 
the  muscles  of  the  dorsal  portion. 

The  fifth  nerve  (PI.  Ill,  figs.  9,  10,  n,  5)  is  quite  small,  and 
may  be  readily  overlooked,  or  considered  as  a  branch  of  the 
sixth  one.  It  arises  close  to  the  base  of  the  latter,  between  it  and 
the  fourth,  and,  on  the  left  side,  seems  indeed  to  be  a  basal 
branch  of  the  sixth  in  many  cases  (PI.  Ill,  fig.  10,  5).  On  the 
right  side,  however,  it  is  distinct  in  origin.  It  is  probably  to  be 


32  OPISTHOBRANCHIATA   OF   BRAZIL 

regarded  as  a  salivary  branch  of  the  sixth,  as  it  is  distributed 
to  the  salivary  gland,  and  thus  would  correspond  to  the  branch 
shown  by  Mazzarelli  in  the  Neapolitan  forms  as  arising  well  up 
from  the  base  of  that  nerve. 

The  sixth  nerve  is  a  strong  and  important  one.  It  cor- 
responds to  No.  Ill  of  Mazzarelli's  text,  and  to  No.  4  of  his  fig.  9, 
tav.  IV.  It  is  shown  in  figs.  9,  10  and  n,  of  PI.  Ill  as  arising 
from  the  posterior  margin  of  the  buccal  ganglion,  and  bifurcating 
after  a  short  course.  Its  anterior  division  soon  gives  off  a  median 
branch  which  breaks  up  in  the  wall  of  the  esophagus,  while  the 
remainder  continues  forward  between  that  organ  and  the  salivary 
gland,  giving  off  slender  branches  to  each,  and  is  finally  dis- 
tributed to  the  roof  of  the  pharyngeal  cavity  at  the  beginning  of 
the  esophagus.  The  posterior  division  of  the  sixth  nerve  forms 
the  esophageo-gastric  nerve  of  each  side.  It  courses  backward 
along  the  esophagus,  over  the  ingluvies,  giving  off  fine  branches 
at  intervals  to  its  walls.  At  the  anterior  boundary  of  the  first 
triturating  stomach  these  two  main  lateral  trunks,  together  with 
several  of  their  branches,  unite  in  a  circular  plexus  of  fibres 
around  the  anterior  margin  of  this  division  of  the  stomach.  From 
this  plexus,  in  which  no  ganglionic  enlargements  were  found, 
nerves  pass  into  the  wall  of  the  digestive  tube,  and  several  (six 
or  more)  branches  course  backward  to  the  second  triturating 
stomach,  in  the  wall  of  which  they  branch  and  anastomose  ir- 
regularly, and  thence  are  continued  further  back  along  the  intes- 
tinal tract  in  a  similar  manner. 

Parieto-visceral  ganglia.  The  position  of  the  parieto-visceral 
ganglia,  the  "deuto-visceral  ganglia"  of  Mazzarelli  ('92)  has  been 
mentioned  above  in  connection  with  the  pleural  ganglia.  The 
two  ganglia  (PI.  Ill,  fig.  14),  are  completely  fused  together, 
forming  a  pear  shaped  mass,  and  show  indications  of  their  double 
nature  at  their  anterior  end  alone,  at  the  entrance  of  the  two 
connectives.  The  right,  or  pleural  ganglion  is  uppermost,  lying 
directly  above  the  left,  or  visceral  ganglia.  From  them  are  given 
off  the  following  important  nerves. 

Visceral  nerves.  From  the  left  visceral  ganglion  arise  three 
nerves.  The  first  of  these  (/.  v.  i),  is  the  smallest.  It  originates 
from  the  postero-dorsal  side  of  the  ganglion,  and,  dividing  into 


TETHYS   DACTYLOMELA    (RANG)  33 

three  main  branches,  is  distributed  to  the  vesicle  of  Swammerdam 
and  its  duct. 

The  second  (/.  v.  2},  is  a  strong,  flattened  nerve  from  the 
posterior  right  side  of  the  ganglion.  It  passes  backward  along 
the  body  wall,  giving  off  a  branch  to  the  liver,  another  to  the  large 
hermaphroditic  duct,  a  third  which  soon  bifurcates,  one  sub- 
division being  distributed  to  the  dorsal  peritoneum  and  muscles, 
the  other,  recurving  forward,  gives  off  a  number  of  delicate 
branches  to  the  dorsal  peritoneum  and  muscles,  and  itself  anasto- 
moses with  a  branch  of  the  third  right  pedal  nerve,  the  united 
nerves  sending  a  branch  to  the  posterior  face  of  the  Organ  of 
Bohadsch.  The  main  trunk  of  the  nerve  continues  backward, 
penetrates  the  dorsal  body  wall,  and  bifurcates  to  the  anal  por- 
tion of  the  alimentary  canal  and  to  the  walls  of  the  siphon. 

Close  to  the  left  of  the  second  nerve  arises  an  equally  strong 
nerve,  very  soon  dividing  into  two  main  trunks,  which  pass 
backward,  diverging  from  each  other.  In  the  largest  specimen 
these  two  trunks  arose  as  separate  nerves  from  the  ganglion. 
The  left  one  (/.  v.  ja),  of  these  sends  a  branch  to  the  liver,  a 
more  slender  one  to  the  muscles  of  the  dorsal  body  wall,  while 
the  main  trunk  curves  upward  around  the  posterior  wall  of  the 
pericardium,  and  thence  forward  in  its  dorsal  wall,  and  is  dis- 
tributed to  the  heart  and  the  kidney.  The  right  main  branch 
(/.  v.  j&),  of  the  third  nerve  sends  a  branch  to  the  liver,  another 
to  the  large  hermaphroditic  duct,  and,  crossing  the  base  of  the 
adnexed  genital  mass,  gives  off  a  branch  to  the  small  genital 
ganglion  lying  upon  it.  Crossing  the  small  hermaphroditic  duct, 
it  gives  off  two  branches  to  it,  and,  continuing  backward,  finally 
terminates  among  the  muscles  in  front  of  the  posterior  portion  of 
the  alimentary  canal. 

Parietal  nerves.  From  the  right,  or  parietal  ganglion  arise 
two  nerves.  A  short  distance  behind  the  junction  of  the  pleuro- 
parietal  connective  with  the  anterior  end  of  the  parietal  ganglion 
the  first  nerve  (r.  p.  /),  is  given  off.  It  is  a  small  trunk,  sending 
a  number  of  branches  to  the  region  of  the  genital  opening,  while 
another  branch  (/a),  courses  forward  and  unites  with  a  branch  of 
the  third  pedal  nerve,  thus  forming  a  parieto-pedal  connective. 
In  one  individual  the  branch  of  the  third  pedal  nerve  continued 
on  to  unite  directly  with  the  parietal  ganglion,  close  to  the  entrance 


34  OPISTHOBRANCHIATA   OF   BRAZIL 

of  the  pleuro-parietal  connective,  simply  receiving  a  small  anasto- 
mosing branch  of  the  first  parietal  nerve. 

The  second  (r.  p.  2},  is  a  very  large  nerve  originating  from 
the  dorsal  side  of  the  posterior  end  of  the  parietal  ganglion.  It 
passes  backward  for  a  short  distance,  and  terminates  in  a  good 
sized  ganglion,  lying  below  the  integument  in  front  of  the 
branchia.  From  this  ganglion  a  nerve  is  sent  to  the  ctenidium 
and  the  wall  of  the  branchial  chamber,  another  penetrates  deeply 
among  the  muscles  of  the  body  wall,  in  front  of  the  kidney  and 
is  probably  distributed  to  the  mantle,  though  its  course  could  not 
be  made  out  with  certainty.  The  main  portion  of  the  ganglion 
supplies  the  osphradium,  or  organ  of  Spengel,  a  conspicuous  oval 
elevation  with  a  depressed  center,  situated  just  in  front  of  and 
slightly  above  the  base  of  the  ctenidium. 

THE  REPRODUCTIVE  SYSTEM. 

The  excellent  work  of  Mazzarelli  ('91)  upon  the  reproductive 
apparatus  of  the  Aplysiidae  has  cleared  up  many  doubtful  points 
in  the  structure  and  functions  of  this  complicated  system,  though 
much  remains  still  to  be  done.  In  the  following  discussion  of 
this  system  in  Tethys  dactylomela  I  use  the  nomenclature  adopted 
by  him. 

The  reproductive  system  of  the  Aplysiidae  is  made  up  of  the 
following  structures,  given  in  their  order  of  occurrence  from 
behind  forward. 

1.  The  ovotestis,  or  hermaphroditic  gland. 

2.  The  small  hermaphroditic  duct. 

3.  The  adnexed  genital  mass,  consisting  of  the  nidamental 
and  albumen  glands,   the   fertilization   chamber,   and   the   con- 
voluted and  spiral  portions  of  the  genital  duct. 

4-  The  spermatocyst  and  duct  of  Cuvier. 

5-  The  large  hermaphroditic  duct. 

6.     The  spermatotheca,  or  vesicle  of  Swammerdamm. 

7-     The  external  spermatic  groove. 

8.     The  penis  and  its  sheath. 

The  ovotestis  forms  the  posterior  end  of  the  visceral  mass, 
being  more  or  less  extensive  depending  upon  the  degree  of  sexual 
maturity  of  the  individual.  In  the  largest  specimen  at  hand 
(140.0  mm.  in  total  length)  the  ovotestis  is  large,  flattened 


TETHYS  DACTYLOMELA    (RANG)  35 

ovoidal  in  shape,  all  its  surface  being  convex,  save  the  anterior 
one,  which  is  irregularly  concave  to  correspond  with  the  surface 
of  the  posterior  end  of  the  liver  and  intestine,  with  which  it  is 
in  close  contact.  Its  surface  is  finely  lobulate,  light  brown  in 
color.  From  the  antero-dorsal  surface  appears  the  light  brown 
small  hermaphroditic  duct,  very  strongly  convoluted  in  its  course, 
0.20  mm.  in  average  diameter,  its  length  being  approximately 
45.0  mm.,  though  this  could  be  estimated  only,  as  it  was  im- 
possible to  straighten  out  its  windings.  Its  distal  end  passes 
obliquely  across  the  ventral  side  of  the  adnexed  genital  mass, 
thence  recurving  dorsally  to  enter  the  latter.  The  "adnexed 
genital  mass"  is  a  term  applied  by  Robert  ('89)  to  designate  a 
complex  made  up  principally  of  the  nidamental  and  albumen 
glands  and  certain  modifications  of  the  genital  duct.  It  is  in 
the  form  of  a  dorso-ventrally  flattened  cone,  situated  obliquely 
to  the  longitudinal  axis  of  the  body.  In  the  smaller  specimens 
it  was  nearly  flat,  in  the  largest  one  quite  large  and  more  pris- 
matic in  form,  its  ventro-anterior  surface  flattened,  the  dorso- 
posterior  one  strongly  arched.  In  length  it  varies  from  2.0  mm. 
to  13.0  mm.,  and  in  width  from  i.o  mm.  to  10.0  mm.  The 
texture  of  the  largest  one  was  very  firm  and  somewhat  brittle, 
the  great  increase  in  size  being  due  to  the  activity  of  the  nida- 
mental and  albumen  glands.  The  small  hermaphroditic  duct, 
entering  the  anterior  side  of  the  basal  portion  of  the  mass,  dilates 
into  an  irregular  cavity,  the  fertilization  chamber,  into  which 
open  the  duct  of  the  albumen  gland  and  the  duct  of  Cuvier  from 
the  spermatocyst.  Beyond  this  fertilization  chamber  the  genital 
duct  becomes  very  much  convoluted  for  a  short  distance,  passing 
thence  over  into  the  spiral  portion,  which  largely  constitutes  by 
its  windings  the  free  portion  of  the  mass,  and  incloses  in  its  loops 
the  greater  portion  of  the  albumen  gland.  Throughout  the  turns 
of  this  spiral  one  side  of  the  duct  is  modified  into  the  nidamental 
gland  by  a  series  of  complicated  foldings,  the  lumina  of  which 
communicate  freely  with  the  duct  proper.  Returning  upon  itself 
from  the  apex  of  the  mass,  the  spiral  portion  widens  out  into 
the  large  hermaphroditic  duct  proper.  By  two  longitudinal  folds 
from  opposite  sides  of  this  large  hermaphroditic  duct  it  is  in- 
completely divided  into  two  conduits.  Owing  to  secondary  twist- 
ing the  relation  at  first  existing  of  a  right  and  a  left  portion 


^6  OPISTHOBRANCHIATA   OF   BRAZIL 

becomes  modified  in  the  course  of  the  duct.  At  the  proximal 
end  the  spiral  portion  of  the  genital  duct  is  continued  into  the 
right  half,  while  that  on  the  left  is  prolonged  into  the  duct  of  the 
spermatocyst  and  the  duct  of  Cuvier,  the  latter  communicating 
with  the  fertilization  chamber.  These  relations  may  be  more 
readily  made  out  in  an  immature  than  in  an  adult  specimen,  and 
best  of  all,  in  serial  sections.  The  spermatocyst  is  a  pear  shaped 
sack,  doubled  upon  itself,  situated  at  the  anterior  margin  of  the 
base  of  the.adnexed  genital  mass,  from  which  it  projects  freely 
for  the  greater  portion  of  its  length.  It  is  ca.  4.9  mm.  long 
and  2.3  mm.  in  maximum  diameter  in  the  largest  specimen 
examined,  but  much  smaller  in  the  others. 

The  large  hermaphroditic  duct  extends  from  the  adnexed 
genital  mass  to  the  vulvar  opening,  with  a  length  of  17.9  mm.  and 
a  diameter  of  0.5  mm.  in  the  largest  individual.  It  is  externally 
marked  to  correspond  to  its  internal  differentiation  into  two 
ducts,  the  one  on  the  right  the  ovo-spermatic,  that  on  the  left 
the  copulatory  duct.  The  latter  duct,  beyond  the  entrance  of  the 
duct  of  the  spermatocyst,  becomes  the  vagina.  The  outer  surface 
of  the  right  of  these  ducts  is  of  a  yellowish  brown  color  and 
transversely  rugose.  The  surface  of  the  left  half  is  smooth  and 
dark  brown.  At  a  distance  from  the  vulvar  opening  of  about 
one-fifth  the  whole  length  of  the  large  hermaphroditic  duct,  the 
duct  of  the  spermatotheca,  or  vesicle  of  Swammerdam  opens  into 
the  left  or  copulatory  duct.  The  vesicle  itself  is  a  large,  spherical 
structure,  5.0  mm.  in  maximum  diameter,  lying  immediately  to 
the  left  of  the  parieto-visceral  ganglion.  By  a  slender  duct, 
0.9  mm.  in  diameter  and  6.2  mm.  in  length,  in  the  largest  speci- 
men, it  communicates  with  the  copulatory  duct. 

The  right  half  of  the  large  hermaphroditic  duct,  which 
functions  alike  as  oviduct  and  vas  deferens,  the  ovo-spermatic 
duct,  the  "ovidutto-deferente"  of  Mazzarelli,  is  continued  forward 
as  a  narrow  external  groove  along  the  right  side  of  the  animal 
from  the  genital  opening  to  the  right  side  of  the  head,  close 
below  the  right  anterior  tentacle.  In  the  largest  specimen  the 
external  spermatic  groove  measured  85.00  mm.  in  length.  Here 
it  is  continued  inward  along  the  inner  wall  of  the  penis  sheath 
to  its  base,  whence  it  recurves  along  the  side  of  the  penis  to  its 
tip,  thus  forming  a  conduit  for  the  spermatozoa  in  copulation. 


TETHYS  DACTYLOMELA    (RANG)  37 

The  penis  sheath  has  moderately  thick,  muscular  walls,  is  nearly 
cylindrical,  slightly  tapering  in  the  retracted  condition.  The 
diameter  of  its  proximal  end  is  2.0  mm.  the  total  length  11.5  mm. 
in  an  individual  of  70.0  mm.  total  length.  To  its  proximal  end 
are  attached  two  strong  retractor  muscles,  a  dorsal  and  a  ventral 
one.  Along  the  outer  dorsal  side  of  the  lumen  the  spermatic 
groove  is  continued  as  a  deep  depression,  the  margins  of  which 
are  elevated  into  prominent  ridges,  and  more  or  less  sprinkled 
with  brown  pigment,  which  in  some  case  is  aggregated  into 
continuous  narrow  longitudinal  lines.  At  the  basal  end  of  the 
penis  sack  this  groove  is  reflected  forward  upon  the  surface  of 
the  penis  along  its  full  length  to  the  tip.  The  penis  is  a  flattened 
muscular  organ,  tapering  distally  to  a  blunt  point.  In  the  speci- 
men of  70.0  mm.  total  body  length,  it  measured  1.9  mm.  in 
maximum  basal  diameter,  with  a  total  length  of  7.5  mm.,  though 
the  presence  of  numerous  transverse  folds  in  the  basal  portion 
indicated  that  this  was  not  the  full  normal  length.  No  trace  of 
pigmentation  is  evident,  nor  is  there  any  specialized  armature 
developed.  The  external  groove  is  ciliated  throughout  its  whole 
extent. 

THE  ORGAN  OF  BOHADSCH. 

The  organ  of  Bohadsch,  or  hypobranchial  gland,  (PI.  Ill, 
fig.  17),  is  a  large  yellowish  white  structure,  irregularly  spherical 
in  form,  and  15.5  mm.  in  diameter  in  the  largest  specimen.  Its 
surface  has  the  characteristic  nodular  appearance  due  to  the 
very  large  cells  of  which  it  is  composed.  In  the  largest  specimen 
the  texture  of  the  gland  was  for  the  most  part  quite  firm,  in  the 
smaller  ones  very  soft,  a  difference  apparently  due  to  the  large 
amount  of  secretion  present  in  the  former.  The  single  duct  is 
short  and  broad,  the  large,  external  opening  conspicuously  located 
below  and  slightly  behind  the  anterior  margin  of  the  base  of  the 
ctenidium. 

EXCRETORY  AND  CIRCULATORY  SYSTEMS. 

The  relations  of  the  kidney  and  the  pericardium  are  sub- 
stantially the  same  as  described  by  Cunningham  ('83)  for  the 
Mediterranean  species,  and  will  not  be  taken  up  in  detail. 

Leland  Stanford  Junior  University  Zoological  Museum, 
Invertebrate  Series  No.  143. 


Tethys  cervina  Dall  and  Simpson. 
Plates.  Ill- VIII,  Figs.  15-35;  Plates  IX-X,  Figs.  39-42. 

Tethys  cervina  Dall  and  Simpson,  The  Mollusca  of  Porto  Rico. 
Bulletin  U.  S.  Fish  Commission,  XX,  1900,  Part  I. 
(Issued  Nov.  29,  1901).  p.  365,  PL  56,  fig.  2. 

One  specimen  of  a  Tethys  different  from  the  foregoing, 
labeled  "Sand  Beach,  Maceio,  Alagoas.  July  31,  1899.  A.  W. 
Greeley  col."  was  found  in  the  collection,  no  other  notes  ac- 
companying it.  In  my  opinion  it  is  identical  with  the  Tethys 
cervina  of  Dall  and  Simpson  taken  at  Mayaguez,  Porto  Rico,  and 
described  in  the  publication  cited  above.  The  description  of  Dall 
and  Simpson  is  as  follows : 

"Body  elongated,  flabby;  mouth  encircled  by  thick  lips;  ten- 
tacles short;  eyes  inserted  in  front  of  the  tentacles.  Swimming 
lobes  thick,  united  behind  at  some  distance  in  front  of  the  hinder 
extremity ;  mantle  orifice  minute ;  mantle  ending  behind  in  a  small 
fold;  foot  narrow,  nearly  smooth. 

"Colors:  The  body  is  a  lurid  gray,  overlaid  with  reticula- 
tions and  blotches  of  darker  color.  It  also  has  scattered,  small, 
nearly  round,  smoky  brown  spots  throughout  its  surface.  The 
foot  is  smoky  brown,  lighter  color  than  the  spots.  The  inner 
edges  of  the  swimming  lobes  are  beautifully  and  distinctly  macu- 
late, with  alternating  light  and  dark  patches.  The  mantle  is 
colored  like  the  body,  but  the  dark  spots  are  wanting,  and  the 
dark  reticulations  are  somewhat  radiating.  Length  7  cm. 

"Shell  with  a  rather  strong  layer  of  lime,  elliptical  in  out- 
line; posterior  sinus  moderate.  Length  of  shell  30;  breadth 
19  mm. 

"Mayaguez,  Porto  Rico." 

The  following  points  are  based  upon  the  Brazil  specimen, 
and  will  serve  as  supplementary  to  the  description  of  the  former 
authors  in  anatomical  details. 

EXTERNAL  CHARACTERS. 

Body  form.  The  body  (PI.  X,  fig.  41),  is  soft,  plump  and 
smooth,  the  head  and  caudal  regions  being  rather  contracted,  the 
remainder  of  the  body  but  little  distorted.  The  total  length  of 
the  specimen  is  40  mm.,  its  width  and  height  being  20  mm. 


TETHYS  CERVINA  BALL  AND  SIMPSON  39 

Color.  The  general  color  is  a  pale  yellowish  gray,  sprinkled 
above  and  on  the  sides  with  minute  dark  brown  spots.  The 
dorsal  surface  of  the  mantle,  covering  the  shell,  is  pale  grayish, 
with  fine  slightly  elongate  markings  of  dark  brown  arranged 
in  inconspicuous  radiate  lines  around  the  minute  opening  into 
the  shell  cavity.  These  radiate  bands  of  dark  color  branch  ir- 
regularly above  the  periphery  of  the  shell  and  merge  into  the 
general  mottling  of  the  body.  The  sides  of  the  body  are  marked 
with  a  few  (eight  to  ten),  irregularly  scattered,  larger,  dark 
brown  flecks,  the  largest  of  which  is  not  over  i.o  mm.  in  diam- 
eter. The  inner  surface  of  the  parapodial  lobes  is  marked  with 
irregular  dark  brown  maculations,  alternating  with  lighter  areas. 
The  foot  is  light  brown  throughout.  These  notes  were  all  made 
from  the  specimens  while  in  formalin.  On  being  transferred  to 
alcohol,  the  darker  colors  gradually  became  much  paler  and  dis- 
appeared more  or  less  completely  throughout. 

Foot.  The  foot  is  very  narrow,  being  strongly  contracted, 
especially  midway  of  its  length,  there  being  reduced  to  2.0  mm.  in 
width,  but  broadening  in  front  to  7.0  mm.,  and  behind  to  4.0 
mm.,  terminating  in  a  short,  bluntly  pointed  tail.  The  anterior 
end  of  the  foot  is  broad  and  blunt  with  rounded  outer  angles. 

Parapodia.  The  parapodial  lobes  are  29  mm.  in  length, 
occupying  nearly  three-fourths  of  the  entire  length  of  the  animal. 
They  are  rather  low  and  not  at  all  prominent,  being  but  10.0  mm. 
in  extreme  height.  The  lobes  are  fleshy,  their  margins  thin  and 
slightly  undulating,  being  slightly  rugose  locally,  a  condition 
probably  due  to  contraction.  The  anterior  ends  of  the  lobes  are 
widely  separated,  the  interval  being  6.5  mm.,  which  is  lessened 
at  the  posterior  end  to  0.5  mm.  though  the  lobes  are  distinct  and 
not  completely  joined  behind  the  siphon. 

Mantle.  The  mantle  area  is  distended  and  plump,  the 
minute  central  opening  into  the  shell  cavity  is  borne  upon  a  low 
papilla,  which  is  rendered  more  conspicuous  by  the  radiate  pig- 
mentation above  described.  On  the  right  side  the  mantle  extends 
in  a  thin-edged  semitranslucent  flap  over  the  gill  cavity.  Poste- 
riorly its  right  margin  is  deeply  notched,  the  edges  being  elevated 
and  rolled  together,  forming  the  prominent  excurrent  siphon, 
which  extends  backward  and  upward  between  the  edges  of  the 
parapodia  to  a  height  of  3.0  mm. 


>0  OPISTHOBRANCHIATA  OF  BRAZIL 

Shell.  The  shell  (PL  X,  fig.  40),  is  very  thin  and  mem- 
branaceous,  the  calcareous  portion,  small  in  amount,  having  been 
broken  and  detached,  was  nearly  all  in  small  fragments  in  the 
shell  cavity.  The  outline  of  the  intact  membranaceous  portion 
is  elliptical,  with  a  moderate  posterior  sinus,  as  described  by 
Dall  and  Simpson.  In  length  it  measures  14.7  mm.  and  in  maxi- 
mum width  9.8  mm.,  though  the  membranaceous  condition  renders 
the  actual  curvature  a  matter  of  some  doubt. 

Pallid  cavity.  The  pallial  cavity  is  roomy,  the  branchial 
plume,  of  the  usual  Tethys  type,  is  nearly  semicircular  in  out- 
line, and  extends  transversely  beneath  the  shell,  its  left  margin 
reaching  well  to  the  left  side,  the  right  tip  projecting  slightly 
from  beneath  the  mantle  margin. 

Anal  and  renal  opening.  The  anal  opening  is  pocket  like, 
and  situated  upon  the  rear  wall  of  the  siphon  tube,  near  its  base. 
In  front  of  it  lies  the  small  inconspicuous  renal  opening  near 
the  base  of  the  branchia. 

Hypobranchial  gland.  The  external  opening  of  the  Organ 
of  Bohadsch,  or  hypobranchial  gland,  lies  upon  the  summit  of  a 
low  thickened  elevation,  just  below  the  anterior  end  of  the  base 
of  the  branchia,  and  2.0  mm.  distant  from  it.  Upon  the  ventral 
surface  of  the  anterior  end  of  the  base  of  the  branchia  is  situated 
the  osphradium,  in  the  form  of  an  oval  yellowish  depression. 
Through  the  transparent  body  wall  of  this  region  many  of  the 
nerves  from  the  parieto-visceral  ganglion  complex  may  be  traced 
for  varying  distances. 

Reproductive  openings.  The  genital  opening  lies  just  in 
front  of  the  anterior  edge  of  the  mantle,  and  is  marked  by  an 
increased  pigmentation  which  is  carried  backward  along  the  body 
wall  toward  the  opening  of  the  Organ  of  Bohadsch.  The  female 
portion  of  the  opening  is  oblique  and  slitlike,  the  portion  lying 
above  it  is  prolonged  forward  as  a  deep  conspicuous  groove 
along  the  side  of  the  body  and  head  to  the  opening  of  the  penis, 
close  to  the  right  anterior  tentacle,  upon  the  side  of  the  head. 

Tentacles.  The  anterior  tentacles  are  strongly  contracted, 
broadly  auriform,  with  a  well  developed  external  groove.  Their 
contracted  condition  precluded  any  even  approximate  measure- 
ments. The  posterior  tentacles,  or  rhinophores,  are  also  strongly 
contracted,  extending  but  1.5  mm.  above  the  surrounding  sur- 


TETHYS  CERVINA  DALL  AND  SIMPSON  41 

face.  They  are  composed  of  the  usual  rolled  plate  with  an 
external,  auriform  slit.  The  bases  are  wide  apart  being  separated 
by  3.0  mm.  distance. 

INTERNAL  ANATOMY. 

The  animal  was  opened  along  the  median  line  of  the  foot 
by  a  longitudinal  incision,  in  order  to  disturb  the  viscera  as 
little  as  possible.  The  peritoneum  is  colorless,  the  liver  light 
chocolate,  the  grey  windings  of  the  intestine  inclosing  it  in  spiral 
turns. 

ALIMENTARY  SYSTEM. 

Pharyngeal  bulb.  The  pharyngeal  bulb  is  nearly  spherical 
and  slightly  elongate,  the  radula  sack  projecting  from  its  ventral 
surface  as  a  prominent,  rounded  eminence.  The  salivary  glands 
are  long,  slender  and  strap  shaped,  their  relations  being  similar  to 
Tethys  dactylomela  and  other  Aplysiidae.  A  pair  of  oblong 
lateral  laminae,  placed  obliquely,  the  mandibular  plates,  (PI.  Ill, 
&£'  I5)»  guard  the  entrance  of  the  pharyngeal  bulb,  being  sep- 
arated above  and  below  by  a  narrow  interval.  The  extreme  width 
of  a  mandible  is  approximately  two-thirds  of  its  greatest  length, 
the  actual  measurements  in  the  individual  at  hand  being  3.00  mm. 
in  length  by  1.9  mm.  in  width.  The  borders  of  the  mandibles 
are  rounded.  Each  lamina  is  made  up  of  a  countless  number 
of  flexible,  nearly  straight  rodlets  with  slightly  dilated  blunt  tips 
(PI.  Ill,  fig.  16),  having  a  maximum  length  of  0.09  mm.  and 
a  diameter  of  0.006  mm.,  the  length  decreasing  toward  the  poste- 
rior border  of  the  lamina,  the  diameter  remaining  the  same,  the 
rodlet  being  somewhat  flattened  antero-posteriorly.  The  bases 
of  the  rodlets  are  supported  by  a  homogenous  horny  cuticula  of 
considerable  thickness. 

Radula.  The  radula  is  of  a  deep  amber  color  in  its  anterior 
older  portion,  becoming  much  lighter  posteriorly.  It  measures 
5.0  mm.  in  greatest  length  by  4.8  mm.  in  width  at  its  posterior 
end,  tapering,  at  first  gradually,  then  more  rapidly  for  the  last 
two-fifths  of  its  length  to  a  rounded  anterior  end.  The  anterior 
rows  of  teeth  are  incomplete,  being  worn  away  and  broken  by 
use.  The  teeth  are  arranged  in  38  rows,  the  last  15  of  which 
are  inclosed  in  the  radula  sheath.  The  number  of  teeth  in  each 


42  OPISTHOBRANCHIATA   OF  BRAZIL 

row  increases  from  16:1  :i6  in  the  oldest  complete  row  to  22  :i  :22 
in  the  thirtieth.  The  dental  formula  of  this  individual  may  be 
expressed  then  as  38x16-22  :i  :i6-22.  The  rhachis  bears  a  single, 
massive  tooth  (PI.  IV,  fig.  23;  PI.  V,  fig.  26,  w),  its  base,  trap- 
ezoidal in  form,  measuring  0.27  mm.  in  width  at  its  posterior 
end  and  0.132  mm.  in  length,  varying  but  slightly  from  these 
dimensions  throughout  the  length  of  the  radula.  The  posterior 
margin  is  slightly  emarginate,  the  anterior  one  deeply  so,  the 
curve  being  carried  up  on  the  anterior  face  of  the  hook  as  a 
broad,  deep  groove.  The  anterior  end  is  prolonged  upward  and 
backward  in  a  strong  hook,  terminating  in  a  stout,  triangular, 
median  cusp,  upon  either  side  of  which  are  borne  two  smaller 
cusps  typically.  The  larger  of  these,  next  to  the  median  one,  is 
from  one-half  to  two-thirds  the  length  of  the  latter;  the  outer 
ones  are  very  much  smaller  and  are  more  variable  in  both  form 
and  size. 

With  the  exception  of  the  outermost  three  to  five  teeth,  the 
lateral  teeth  are  strongly  hooked  and  of  similar  form,  decreasing 
gradually  in  size  toward  the  outer  borders  of  the  radula  (PI.  IV, 
figs.  23-25).  Each  lateral  tooth  (PI.  IV,  figs.  23-25;  PI.  V,  figs. 
26-30),  consists  of  a  stout  oblong  base  obliquely  placed,  from 
the  dilated  anterior  end  of  which  arises  a  stout  hook,  terminating 
in  a  triangular  cusp.  The  sides  of  this  cusp  bear  four  to  ten 
denticles,  quite  small  near  the  tip  and,  in  general,  increasing  in 
size  toward  the  base,  though  irregularities  in  this  are  not  infre- 
quent. Upon  the  inner  side  of  each  tooth,  at  the  base  of  the  hook, 
the  series  of  denticles  is  terminated  usually  by  a  very  large  and 
broad  denticle,  while  upon  the  outer  flank  of  the  main  cusp  a 
series  of  two  or  three  smaller  cusps  is  borne.  In  the  radula  of 
Tethys  dactylomela  there  is  but  one  external  cusp  in  this  position, 
which  is  usually  itself  denticulate,  but  in  T.  cervina  the  margins 
are  uniformly  smooth  (cf.  PI.  I,  figs.  1-5,  and  PI.  IV  and  V,  figs. 
23-30).  Indications  of  a  fourth  lateral  cusp  at  the  extreme  end 
of  this  series  are  frequently  found.  The  first  ten  laterals  are 
approximately  equal  in  size  (PI.  IV,  figs.  23-24,  i-io),  the  re- 
maining ones  decrease  toward  the  outer  border  of  the  radula  (PI. 
IV,  fig.  25),  the  hook  finally  becomes  rudimentary  and  disappears 
altogether,  the  outermost  three  to  five  teeth  being  reduced  to 
oblong  flattened  plates  (PI.  V,  fig.  28).  The  teeth  of  this  species 


TETHYS  CERVINA  DALL  AND  SIMPSON  43 

are  in  general  about  two-thirds  the  size  of  those  of  Tethys 
dactylomela. 

The  visceral  mass  nearly  fills  the  body  cavity  of  the  animal. 
It  is  made  up  of  the  esophagus,  the  three  divisions  of  the  stomach, 
and  the  intestine,  the  latter  inclosing  in  its  windings  the  liver 
and  the  ovotestis. 

Esophagus  and  stomach.  The  esophagus  is  short  and  rather 
thin  walled,  dilating  into  the  very  ample  first  stomach,  or  in- 
gluvies  (PI.  VI,  fig.  31,  ingl.),  a  thin  walled  sack,  densely  packed 
with  fragments  of  algae.  The  whole  alimentary  canal  is  spirally 
twisted  from  left  to  right,  clockwise.  The  ingluvies  occupies 
about  one  turn  of  this  spiral,  the  second,  or  grinding  stomach 
(PI.  VI,  fig.  31,  m.  St.),  together  with  the  third  gastric  division 
completing  about  one-half  of  the  second  turn.  The  anterior  end 
of  the  ingluvies  dilates  rather  suddenly  from  the  esophageal  tube, 
the  posterior  end  tapering  more  gently  to  the  broad  band  like 
circular  constriction  in  the  canal,  marking  externally  the  limits 
of  the  thick  walled,  muscular,  second,  or  grinding  stomach  (PI. 
VI,  fig.  31,  m.  st.).  This  portion  is  about  4.0  mm.  in  length  by 
5.0  mm.  in  diameter  at  its  anterior  end,  tapering  somewhat  poste- 
riorly. Its  inner  surface  bears  a  number  of  strong  horny  teeth, 
arranged  in  five  somewhat  irregular  rows,  the  anterior  ones  of 
which  contain  the  smaller  teeth,  the  succeeding  ones  increasingly 
larger,  and  the  last  two  the  largest.  The  tips  of  this  gastric  arma- 
ture meet  in  the  center  of  the  lumen  in  the  contracted  condition, 
thus  making  a  most  effective  gastric  mill.  In  general  the  form  of 
these  teeth  is  the  same  throughout,  being  that  of  a  four  sided 
pyramid,  the  base  a  rhomb  in  outline  with  one  of  the  acute  angles 
directed  forward.  In  the  largest  teeth  of  the  posterior  rows  (PI. 
Ill,  fig.  21 ),  the  crest  is  either  single,  rounded  and  bluntly  pointed, 
or  wedge  shaped,  being  prolonged  into  a  transverse  ridge.  In 
most  cases  this  ridge  shows  three  distinct  summits,  separated  from 
each  other  by  shallow  depressions,  which  are  continued  downward 
upon  the  anterior  face  in  two  deep  grooves,  while  the  posterior 
face  is  more  uniformly  convex.  The  base  frequently  presents 
a  transverse  median  depression  upon  its  ventral  surface,  cor- 
responding in  position  to  the  region  of  greatest  elevation  above 
(PI.  Ill,  fig.  21 ).  The  smaller  teeth,  found  in  the  two  anterior 
rows,  have  a  single  groove  upon  the  anterior  face,  carried  up  to 


44  OPISTHOBRANCHIATA  OF  BRAZIL 

the  cusp,  which  is  single,  and  may  present  the  form  of  a  point 
(PL  III,  %s.  18,  19),  or  of  a  transverse  wall  with  a  concave  front 
face  (PL  HI,  fig.  20).  At  the  anterior  margin  of  each  of  these 
smaller  teeth  rises  a  lower  median  cusp,  which  is  connected  by 
a  lower  sloping  ridge  with  the  posterior  higher  main  one  (PL  III, 
figs.  18,  19).  All  these  teeth  are  borne  upon  thickened  disks  of 
epithelium  with  elevated  margins  and  concave  central  portions, 
corresponding  to  the  convex  bases  of  the  teeth. 

The  third  stomach  (PL  VI,  fig.  31*  3  *'•)»  is  nearly  as  thin 
walled  as  the  first  one,  and  is  about  one-fourth  as  long,  being  6.0 
mm.  in  length  upon  its  greater  curvature.  It  increases  in  diam- 
eter from  the  posterior  border  of  the  second  stomach  for  a  short 
distance,  then  tapers  as  it  becomes  imbedded  in  the  posterior 
visceral  mass.  The  inner  wall  of  the  third  stomach  bears  a 
circular  band  of  small  flattened  horny  teeth,  approaching  close 
to  the  anterior  margin  of  the  stomach  on  the  side  of  the  lesser 
curvature,  and  arching  backward  from  this  region  around  the 
greater  curvature,  there  reaching  a  distance  of  4.0  mm.  from  the 
anterior  margin.  The  tooth  bearing  zone  is  2.0  mm.  in  width 
throughout  its  whole  extent.  The  teeth  are  much  more  highly 
developed  than  in  Tethys  dactylomela,  are  curved  and  conical  in 
shape  (PL  III,  fig.  22),  and  are  much  more  irregularly  arranged 
than  in  the  second  stomach,  small  and  large  teeth  being  inter- 
mingled. Behind  this  tooth  bearing  zone  a  few  small  and  slender 
teeth  of  similar  shape  are  irregularly  scattered. 

Intestine.  The  intestine  is  twisted  in  a  slightly  more  com- 
plicated way  than  the  gastric  region  just  described,  the  greater 
part  describing  a  wide  loop  upon  the  left  side  and  upper  surface, 
the  terminal  portion  then  returning  to  the  simple  spiral  form 
(PL  VI,  fig.  31,  int.).  Within  the  coils  of  the  intestine  are  in- 
closed the  liver  and  the  ovotestis,  the  outer  surface  of  the  former 
showing  throughout  its  whole  extent,  though  so  deeply  imbedded 
in  the  liver  as  to  everywhere  present  a  smooth  surface.  It  is  a 
simple,  thin-walled  tube  save  at  the  most  anterior  portion,  where 
it  is  dilated  somewhat,  and  receives  a  slender  diverticulum,  the 
"hepatic  coecum"  of  Mazzarelli  and  Zuccardi  (PL  VI,  fig.  31  h. 
cos.).  Upon  opening  the  intestine  at  its  anterior  end  a  large 
cavity  in  the  substance  of  the  liver  is  disclosed  (PL  VI,  fig.  32), 
into  which  open  three  large  principal  ducts  and  several  smaller 


TETHYS  CERVINA  DALL  AND  SIMPSON  45 

ones,  which  ramify  throughout  the  liver,  conveying  its  secretion 
to  the  central  biliary  cavity.  Into  the  posterior  side  of  this 
chamber  opens  the  hepatic  coecum  (PI.  VI,  fig.  32,  h.  cce.),  a 
narrow  curved  cylindrical  tube,  at  first  imbedded  in  the  liver, 
but  appearing  at  its  surface  for  the  distal  third  of  its  length.  It 
is  9.0  mm.  in  length,  the  diameter  varying  from  i.o  mm.  to  1.25 
mm.  It  is  traversed  by  two  longitudinal  folds,  arising  from 
opposite  sides,  the  one  higher  than  the  other,  which  meet  and 
overlap,  thus  dividing  the  lumen  into  two  practically  separate, 
longitudinal  portions,  united  at  the  blind,  distal  end.  At  the 
opening  of  the  coecum  into  the  bile  chamber,  the  anterior  one  of 
these  communicates  freely  with  the  latter,  its  walls  being  grooved 
and  folded  in  prolongation  of  similar  folds  and  grooves  in  the 
wall  of  the  bile  chamber.  The  posterior  half  of  the  coecum 
communicates  as  a  deep  groove  with  the  intestine,  one  of  the 
median,  longitudinal  folds  in  the  wall  of  the  coecum  being 
continued  across  the  opening  of  the  bile  chamber  and  down  into 
the  intestine  (PI.  VI,  fig.  32,  /.  r.),  there  gradually  merging  with 
its  wall. 

THE  CENTRAL  NERVOUS  SYSTEM. 

The  central  nervous  system  (PI.  VII,  fig.  34)  is  made  up  of 
three  pairs  of  ganglia  resting  upon  the  posterior  end  of  the  phar- 
yngeal  bulb,  and,  with  their  commissures,  encircling  the  com- 
mencement of  the  esophagus.  These  are  the  cerebral,  the  pedal 
and  the  pleural  ganglia,  each  pair  united  by  commissures  of 
varying  length,  while  the  ganglia  of  each  side  are  united  in  a 
triangular  grouping  by  the  cerebro-pedal,  the  cerebro-pleural, 
and  the  pleuro-pedal  connectives.  Close  to  these  ganglia,  and  to 
be  included  with  them  in  the  central  nervous  system,  are  the 
buccal  ganglia,  situated  on  the  ventral  side  of  the  esophagus,  and 
forming  with  their  cerebral  connections,  the  cerebro-buccal  con- 
nectives, another  ring  around  the  anterior  end  of  the  alimentary 
canal.  These  structures  will  be  taken  up  briefly  in  the  following 
description.  On  plate  VII  is  figured  a  dorsal  view  of  the  whole 
central  nervous  system  of  Tethys  cervina,  excepting  the  buccal 
ganglia,  together  with  the  origins  of  the  nerves  taken  up  in  the 
following  pages.  As  in  the  similar  figure  of  the  preceding  species 
of  Tethys,  given  on  Plate  II,  the  nerves  are  numbered  in  the 


.5  OPISTHOBRANCHIATA  OF  BRAZIL 

order  of  their  appearance  from  in  front  and  above  downward 
and  backward.  All  abbreviations  in  the  following  description 
refer  to  fig.  34,  Plate  VII,  unless  otherwise  indicated. 

Cerebral  ganglia.  The  cerebral  (cer.  £.)  ganglia  are  com- 
pletely fused  together  into  a  large  quadrilateral  mass,  all  traces 
of  their  primitive  separation  into  right  and  left  moities  having 
disappeared.  The  nodulated  dorsal  surface  of  the  mass  is  highly 
arched,  the  ventral  slightly  concave.  In  width  the  complex 
measured  1.5  mm.,  in  length  0.9  mm.  and  in  thickness  0.7  mm. 
A  slender,  sub-esophageal,  cerebral  commissure  passes  below  the 
esophagus,  connecting  the  halves  of  the  ganglionic  mass  together 
ventrally.  In  fig.  34,  PI.  VII,  s.  c.  com.,  it  is  seen  inclosed  in  the 
same  sheath  of  connective  tissue  as  the  pedal  commissure  and 
lying  at  its  anterior  margin. 

Cerebral  nerves.  From  the  cerebral  ganglia  arise  six  pairs 
of  nerves  and  three  connectives,  the  origins  of  which  are  the 
same  for  each  side. 

The  first  cerebral  nerve  (c.  /)  arises  from  the  anterior  outer 
face  of  the  ganglion,  and  courses  forward  to  its  distribution  to 
the  skin  and  the  muscles  of  the  mouth  region. 

The  second  cerebral  nerve  (c.  2}  arises  immediately  behind 
the  first,  and  is  much  larger.  It  curves  forward  along  the 
pharyngeal  bulb,  giving  off,  midway  of  its  length,  a  strong  outer 
branch  to  the  anterior  tentacle,  in  which  it  terminates  in  a  small 
ganglion.  The  main  trunk  breaks  up  into  a  number  of  divisions, 
which  are  distributed  to  the  muscles  and  integument  of  the  mouth 
region. 

The  third  cerebral  nerve  (c.  5)  arises  from  the  upper  dorsal 
border  of  the  ganglion,  and  is  distributed  mainly  to  the  rhino- 
phore,  in  which  it  terminates  in  a  small  ganglion.  It  also  gives 
off  two  or  three  slender  branches,  the  first  and  largest  of  which 
forms,  apparently,  an  anastomosis  with  the  optic  nerve.  It  is 
not  a  true  fusion,  however,  the  two  nerves  being  merely  united 
in  a  common,  epineural  sheath  for  a  short  distance.  The  dis- 
tribution of  this  and  the  other  slender  branches  of  the  third 
nerve  is  to  the  integument  in  the  neighborhood  of  the  eye  and 
rhinophore.  Upon  the  right  side  a  true  anastomosis  occurs  with 
a  branch  of  the  second  pedal  nerve,  as  shown  at  x.  in  the  figure 
and  to  be  described  further  on. 


TETHYS  CERVINA  DALL  AND  SIMPSON  47 

The  fourth,  or  optic  nerve  (c.  4)  is  slender,  long  and  un- 
branched.  It  arises  from  the  dorsal  margin  of  the  ganglion  and 
passes  outward  and  upward  to  the  eye.  No  special  optic  gan- 
glion can  be  made  out  at  its  base  without  serial  sections. 

The  fifth  cerebral  nerve  (c.  5)  arises  from  the  postero-lateral 
face  of  the  ganglion,  immediately  above  the  origin  of  the  cerebro- 
buccal  connectives.  It  is  a  rather  slender  nerve,  passing  forward 
and  ramifying  to  the  muscles  of  the  mouth  region.  That  of  the 
right  side  sends,  in  addition,  a  branch  to  the  penis. 

The  sixth  cerebral,  or  auditory  nerve,  is  closely  associated 
with  the  cerebro-pedal  connectives  and  is  not  visible  in  dorsal 
view.  It  arises  close  to  the  base  of  the  connective,  and  follows 
it  to  the  upper  face  of  the  pedal  ganglion  where  it  terminates  in 
the  otocyst,  being  throughout  its  course  inclosed  in  the  connective 
tissue  sheath  of  the  cerebro-pedal  connective  (c.  p.  con.). 

Three  sets  of  connectives  arise  from  the  cerebral  ganglia, 
the  cerebro-buccal,  the  cerebro-pleural  and  the  cerebro-pedal. 
The  first  named  pair  is  the  longest,  arising  from  the  outer  ventral 
margins  of  the  ganglia,  and  encircling  the  anterior  end  of  the 
esophagus  to  unite  with  the  buccal  ganglia  beneath.  They  are 
not  visible  in  fig.  34.  The  cerebro-pedal  connectives  (c.  p.  con.), 
pass  obliquely  outward  and  backward  from  their  origins  upon 
the  postero-ventral  margin  of  the  cerebral  ganglia  to  the  pedal 
ganglia  (ped.  g.).  They  are  short  and  thick,  and  are  inclosed 
in  a  strong  connective  tissue  sheath  with  the  cerebro-pleural  con- 
nectives (c.  pi.  con.),  which  are  of  nearly  equal  diameter,  but  less 
long. 

Pedal  ganglia.  The  pedal  ganglia  (ped'.  g.),  are  rounded 
flattened  structures,  measuring  1.4  mm.  in  diameter  and  0.6  mm. 
in  maximum  thickness.  They  are  connected  below  the  esophagus 
by  a  strong  commissure  (p.  com.),  i.o  mm.  long  and  0.15  mm. 
wide.  A  much  longer  and  quite  slender  parapedal  commissure 
(p.  p.  com.),  arising  from  the  lower  posterior  margin  of  each 
ganglion  also  unites  the  two.  Upon  the  upper  margin  of  the 
pedal  ganglia  are  received  the  cerebro-pedal  connectives  and  just 
behind  them  the  very  short  pleuro-pedal  ones.  From  each  gan- 
glion ten  nerves  are  given  off.  These  will  be  described  for  the 
right  side,  any  difference  which  may  exist  upon  the  opposite  one 
being  noted.  The  nerves  are  taken  in  order  and  numbered  in  the 


4g  OPISTHOBRANCHIATA  OF  BRAZIL 

series  from  the  upper  anterior  margin  of  the  ganglion,  downward 
and  backward.  For  the  nerves  originating  along  the  outer  margin 
of  the  ganglion  this  presents  no  difficulties,  but  those  nerves 
which  arise  from  the  median  portion  of  the  ventro-anterior  face 
are  of  necessity  more  arbitrarily  assigned  their  position  in  the 
series  as  indicated. 

Pedal  nerves.  The  first  nerve  (/),  is  a  very  slender  one, 
arising  from  the  upper  ventro-anterior  face  of  the  pedal  ganglion, 
just  below  and  external  to  the  entrance  of  the  cerebro-pedal  con- 
nective, and  very  close  to  the  origin  of  the  second  nerve.  It 
passes  outward  and  forward  to  the  integument  in  the  eye  region. 

The  second  nerve  (2),  is  similar  in  size  to  the  first  nerve, 
arises  quite  close  to  it,  and  in  some  specimens  may  possibly  be 
found  to  branch  from  a  common  trunk  with  it.  It  courses  out- 
ward and  upward,  dividing  into  two  branches  near  the  proximal 
end  of  the  penis.  The  dorsal  one  of  these  branches  passes  to  the 
dorsal  retractor  of  the  penis  sheath,  the  ventral  subdivision  gives 
off  a  twig  which  anastomoses  with  a  branch  of  the  third  cerebral 
nerve,  another  to  the  ventral  retractor  of  the  penis  sheath,  and 
then  courses  forward  below  the  penis  to  its  distal  end,  giving  off 
several  minute  branches  to  it.  The  extreme  ramifications  of  this 
portion  of  the  nerve  are  to  the  anterior  end  of  the  penis  sheath 
and  to  the  muscles  and  integument  surrounding  it.  Upon  the 
left  side  this  nerve  is  distributed  to  the  muscles  and  integument 
of  the  body  wall  from  the  eye  forward. 

In  Tethys  dactylomela  these  two  nerves,  numbers  one  and 
two  of  T.  cervina,  are  represented  by  but  one  nerve,  described  as 
the  first  on  page  27,  and  so  figured  in  PL  II,  p.  I,  but  with  the  same 
distribution  as  the  first  and  second  here  described. 

The  third  pedal  nerve  (j)  arises  from  the  upper  external 
margin  of  the  ganglion  and  bifurcates  almost  immediately.  The 
anterior  one  of  these  branches  divides  in  turn  almost  at  once, 
one  branch,  ja,  forming  an  anastomosis  with  the  first  pleural 
nerve  (pi.  /),  being  like  it  distributed  to  the  dorsal  peritoneum 
and  musculature  back  to  the  heart  region,  the  other,  jb,  passing 
directly  backward  to  a  similar  distribution.  The  posterior  main 
branch  (jc)  is  much  longer  and  is  shown  in  detail  in  fig.  35  of 
PI.  VIII.  It  curves  backward,  sends  off  a  branch  (fig.  35,  56),  to 
the  right  lateral  retractor  muscle  of  the  head,  and  to  the  body  wall 


TETHYS  CERVINA  DALL  AND  SIMPSON  49 

above  it,  another  (fig.  35,  5^),  to  the  Organ  of  Bohadsch,  or 
hypobranchial  gland,  and  finally  (fig.  35,  J/),  unites  with  the 
first  nerve  from  the  right  parietal  ganglion,  thus  forming  a 
parieto-pedal  connective.  From  the  above  mentioned  branch 
(fig.  35,  j6),  to  the  lateral  retractor  of  the  head  a  branch  is  given 
off  which  courses  backward  along  the  body  wall,  passes  beneath 
the  right  margin  of  the  Organ  of  Bohadsch,  and  well  beyond  the 
latter  forms  an  anastomosis  at  an  acute  angle  with  the  recurrent 
branch  (fig.  35,  2c)  of  the  second  nerve  (fig.  35,  /.  v.  2),  of  the 
left  visceral  ganglion,  which  also  sends  a  branch  to  the  Organ 
of  Bohadsch,  as  will  be  described  below.  In  Tethys  dactylomela 
the  third  pedal  nerve  is  represented  by  two  separate  nerves,  the 
second  and  third  of  the  description  on  page  28,  they  correspond- 
ing in  their  distribution  to  the  third  nerve  alone  of  T.  cervina. 

The  fourth  pedal  nerve  (4)  is  long  and  slender,  arising  from 
the  outer  margin  of  the  ganglion  and  passing  backward  to  the 
parapodium  of  the  same  side. 

The  fifth  pedal  nerve  (5)  is  a  strong  one  from  the  median 
lateral  margin  of  the  ganglion.  Close  to  its  origin  it  gives  off  a 
slender  branch  (50)  which  might  possibly  be  considered  a  separate 
nerve,  though  its  distribution  is  the  same  as  that  of  the  main 
nerve,  to  the  parapodium.  In  T.  dactylomela  a  similar  branch 
is  given  off  from  the  fifth  nerve,  but  its  origin  is  further  removed 
from  the  base  of  that  nerve.  Its  distribution  is  the  same  as  that 
here  indicated. 

The  sixth,  or  posterior  pedal  nerve  (6)  is  the  longest  of  the 
nerves  from  the  pedal  ganglion.  It  arises  from  the  mid-lateral 
margin  of  the  ganglion,  curves  backward,  unbranched  for  over 
one-half  of  its  course,  and  is  distributed  to  the  posterior  portion 
of  the  foot. 

The  seventh  pedal  nerve  (/)  arises  upon  the  lower  portion 
of  the  ventro-anterior  face  of  the  ganglion,  below  the  origin  of 
the  first  and  second  nerves.  Like  these  and  the  ninth  is  is  closely 
imbedded  in  the  connective  tissue  surrounding  the  pharyngeal 
bulb  and  may  be  dissected  out  with  some  difficulty.  A  branch  of 
the  seventh  forms  an  anastomosis  with  the  ninth,  and  both  are 
distributed  to  the  muscles  and  integument  of  the  side  of  the  head. 
The  nerves  of  both  sides  are  alike  in  origin  and  distribution. 

The  eighth,  or  median  pedal  nerve  (<?)   is  a  strong  trunk 


C0  OPISTHOBRANCHIATA   OF   BRAZIL 

arising  from  the  outer  lower  margin  of  the  ganglion  and  is  dis- 
tributed to  the  middle  region  of  the  foot.  Upon  the  left  side  its 
origin  is  slightly  more  removed  from  that  of  the  tenth. 

The  ninth  pedal  nerve  (p)  arises  from  the  ventral  portion  of 
the  lower  anterior  face  of  the  ganglion.  It  is  quite  slender  and 
forms  an  anastomosis  with  a  branch  of  the  seventh.  Its  distri- 
bution has  been  given  above  in  connection  with  that  of  the  latter 
nerve,  and  is  similar  on  both  sides. 

The  tenth,  or  anterior  pedal  nerve  (10),  is  a  large  trunk 
from  the  outer  lower  margin  of  the  ganglion.  It  doubles  forward 
in  four  main  divisions  beneath  the  pharyngeal  bulb  and  is  dis- 
tributed to  the  anterior  portion  of  the  foot. 

The  order,  arrangement  and  distribution  of  the  pedal  nerves 
is  the  same  for  the  two  species  of  Tethys  here  studied,  but  they 
disagree  markedly  with  the  accounts  given  by  other  authors, 
notably  Von  Ihering  ('77)  and  Mazzarelli  ('93),  for  the  Medi- 
terranean forms.  Until  I  am  able  to  secure  material  for  a  de- 
tailed comparison  of  all  the  species  concerned  I  cannot  explain 
this  lack  of  agreement.  Von  Ihering  ('77)  describes  and  figures 
but  six  nerves  from  each  ganglion.  Mazzarelli  ('93)  describes 
and  figures  seven  paired  pedal  nerves  and  one  unpaired  one  upon 
the  right  side,  and  two  unpaired  ones  upon  the  left,  their  order 
and  distribution  not  agreeing  with  the  Brazilian  forms,  while 
Lacaze-Duthiers  ('87)  found  but  six  in  all. 

Pleural  ganglia.  The  pleural  ganglia  (pi.  £.),  are  situated 
just  above,  and  in  contact  with  the  upper  surface  of  the  pedal 
ganglia,  with  which  they  are  connected  by  the  very  short  pleuro- 
pedal  connectives.  They  are  about  one-third  the  size  of  the  pedal 
ganglia,  and  are  spheroidal  in  outline,  measuring  0.5  mm.  in 
greatest  diameter.  They  are  made  up  of  large  conspicuous  cells, 
which  give  their  surface  a  knobbed  appearance.  Contrary  to  the 
descriptions  and  figures  of  Von  Ihering  ('77),  and  Mazzarelli 
('93) >  I  find  that  the  pleural  ganglia  give  rise  to  the  following 
nerves. 

Pleural  nerves.  From  the  left  pleural  ganglion  arise  two 
nerves.  The  first  (pi.  i),  is  a  slender  nerve  from  the  superior 
face  of  the  ganglion.  It  passes  outward  and  downward,  receives 
an  anastomosing  branch  from  the  third  pedal  nerve  and  ramifies 


TETHYS  CERVINA  BALL  AND  SIMPSON  51 

to  the  peritoneum  and  the  muscles  of  the  dorsal  body  wall,  just 
above  and  behind  the  region  of  the  central  nervous  system. 

The  second  pleural  nerve  (pi.  2),  arises  just  exterior  to  the 
origin  of  the  pleuro-visceral  connective.  It  passes  backward  as 
a  long  slender  unbranched  trunk  in  the  dorsal  peritoneum,  to  the 
region  of  the  pericardium,  in  the  anterior  wall  of  which  it  ramifies 
among  the  muscles. 

From  the  right  pleural  ganglion  but  one  nerve  (pi.  i},  is 
given  off.  It  corresponds  to  the  first  one  of  the  left  side  and  has 
a  similar  distribution.  It  also  receives  an  anastomosing  branch, 
30,,  from  the  third  pedal  nerve  of  the  right  side. 

From  the  median  posterior  face  of  the  ganglia  arise  the  long 
and  strong  connectives,  which  pass  backward  to  the  ganglion  com- 
plex upon  the  visceral  loop,  situated  immediately  below  the 
anterior  boundary  of  the  pericardium.  The  left  of  these  connect- 
ives (pi.  v.  con.},  is  slightly  longer  than  its  fellow,  measuring 
14.0  mm.,  as  compared  with  12.0  mm.  for  that  of  the  right  side. 
The  right  of  these  (pi.  par.  con.},  is  the  pleuro-parietal  connect- 
ive, the  left  the  pleuro-visceral  one.  Their  peripheral  relations 
will  be  taken  up  further  on. 

Buccal  ganglia.  The  buccal  ganglia  are  oval  in  outline, 
each  measuring  0.45  mm.  in  length  by  0.42  mm.  in  width,  and 
are  connected  by  a  broad  commissure  0.18  mm.  in  length,  so  that 
the  two  ganglia  are  distinctly  separated  from  each  other,  though 
enveloped  in  a  common  connective  tissue  sheath.  From  the 
anterior  median  face  is  given  off  a  strong  unpaired  nerve  as  in 
Tethys  dactylomela,  soon  bifurcating  to  the  muscles  of  the  rotella. 
From  the  outer  side  of  each  ganglion  four  nerves  are  given  off, 
in  addition  to  the  cerebro-buccal  commissures.  These  nerves  are 
distributed  to  the  pharyngeal  bulb,  the  salivary  glands  and  the 
esophagus,  but  their  ramifications  were  not  worked  out  in  detail. 

Parieto-visceral  ganglia.  The  parieto-visceral  ganglion 
group  (PI.  VIII,  fig.  35,  par.  v.  g.),  is  situated  beneath  the  dorsal 
wall  of  the  body,  slightly  to  the  right  of  the  median  line  and 
directly  below  the  anterior  border  of  the  pericardium.  The  com- 
position of  the  group  as  made  up  of  a  right  and  left  portion, 
fused  in  the  median  plane,  can  be  readily  made  out,  but  any 
further  division  into  component  ganglia  is  not  indicated  in  surface 
view.  The  double  nature  of  the  group  is  marked  only  at  the 


C2  OPISTHOBRANCHIATA   OF   BRAZIL 

anterior  end  by  the  entrance  of  the  respective  connectives,  and 
by  a  slight  groove  upon  the  anterior  face.  The  nerve  cells  of 
these  ganglia  are  of  the  usual  gigantic  type  found  in  Opistho- 
branchs  generally,  and  cause  the  surface  of  the  ganglia  to  present 
a  series  of  irregular  protuberances. 

Parietal  nerves.    From  the  right  or  parietal  ganglion  arise 
two  nerves. 

1.  The  vulvar  nerve  (PI.  VIII,  fig.  35  ;  P1-  x»  fig-  42,  r.  p.  i), 
is  a  delicate  trunk  from  the  right  side,  soon  bifurcating  into  (a), 
a  branch  (figs.  35,  42,  r.  p.  la)  coursing  forward  and  anastomos- 
ing with  a  branch  of  the  third  pedal  nerve  (PI.  VIII,  fig.  35,  J/), 
forming  the  pedo-parietal  connective  before  described,  and  (b), 
the  vulvar  nerve  proper  (PI.  VIII,  fig.  35  J  P1-  x>  fig-  42,  r.  p.  ib), 
which  passes  to  the  anterior  end  of  the  large  hermaphroditic  duct 
and  to  the  integument  surrounding  it. 

2.  The  second,  or  osphradio-ctenidial  nerve  (PI.  VIII,  fig.  35 ; 
PI.  X,  fig.  42,  r.  p.  2),  is  a  very  strong  trunk,  in  diameter  quite 
reaching  that  of  the  pleuro-parietal  connective.     It  arises  from 
the  upper  right  side  of  the  parietal  ganglion,  passes  outward  and 
backward  in  a  curve  to  the  right,  thence  upward  to  the  anterior 
base  of  the  ctenidium,  where  it  unites  with  the  large  ganglion  of 
the  osphradium  (PL  VIII,  fig.  35;  PL  X,  fig.  42,  osp.  £.),  lying 
immediately  below  the  integument,  and  visible  through  it.     The 
osphradium  is  visible  externally  as  a  depressed  oval  area  of  a 
light  yellowish  color,  situated  upon  the  ventral  face  of  the  anterior 
portion  of  the  base  of  the  ctenidium.    It  is  0.4  mm.  in  length  by 
o.i  mm.  in  width.    From  this  osphradial  ganglion  arise  two  rather 
strong  nerves,  one  (PL  VIII,  fig.  35;  PL  X,  fig.  42,  osp.  g.  /), 
passing  forward,  its  several  branches  being  distributed  among  the 
large  gland  cells  of  the  anterior  and  lateral  margins  of  the  mantle. 
The  other  nerve  from  the  osphradial  ganglion  passes  a  short  dis- 
tance to  the  left  and  terminates  in  a  smaller  branchial  ganglion 
(PL  X,  fig.  42,  ct.  g.)  at  the  right  of  the  pericardium.    From  this 
ganglion  a  main  branchial  nerve  (PL  X,  fig.  42,  ct.  n.),  passes 
backward  to  the  ctenidium,  and  several  very  delicate  nerves  are 
also  given  off  to  the  pericardial  wall  and  are  lost  among  its 
fibres. 

Visceral  nerves.    The  left,  or  visceral  ganglion  is  equal  in 
size  to  the  right  parietal  one.    At  its  anterior,  more  pointed  end  it 


TETHYS   CERVINA  BALL  AND  SIMPSON  53 

receives  the  distal  end  of  the  left  pleuro- visceral  connective.    From 
its  posterior  portion  it  gives  origin  to  the  following  four  nerves. 

1.  From  near  the  posterior  median  line  arises  a  slender 
nerve  (PI.  X,  fig.  42,  /.  v.  /),  which  immediately  bifurcates  to  the 
Vesicle  of  Swammerdam,  or  spermatotheca,  and  its  duct,  a  slender 
branch  being  also  continued  to  the  adjacent  peritoneum. 

2.  A  large  nerve  (PI.  VIII,  fig.  35,  /.  v.  2),  given  off  from  the 
posterior  right  side  of  the  ganglion,  passes  obliquely  backward 
to  the  right,  crossing  the  large  hermaphroditic  duct  midway  of 
its  length,  to  the  posterior  end  of  the  body.    It  gives  off  a  number 
of  slender  branches  to  the  dorsal  peritoneum,  and  a  larger  one, 
20,,  to  the  liver,  separating  from  the  main  nerve  near  its  origin, 
but  continued  with  it  in  a  common  epineural  sheath  for  some 
distance.    A  little  beyond  the  middle  of  its  course  the  second  nerve 
gives  off  a  moderately  strong  recurrent  branch  to  the  right,  20, 
and  then  passes  straight  backward,  2b,  bifurcating  to  the  anal 
portion  of  the  intestine,  and  to  the  siphon.     From  the  recurrent 
nerve,  2c,  a  long,  posterior  branch,  2d,  is  given  off,  which  is  dis- 
tributed to  the  peritoneum  in  the  median  posterior  region  near 
the  rectum ;  the  main  nerve,  curving  forward,  sends  one  or  two 
very  delicate  branches  to  the  peritoneum,  a  stronger  one,  2e,  to 
the  posterior  face  of  the  Organ  of  Bohadsch,  passes  beneath  the 
right  margin  of  the  latter  gland,  and  forms  an  anastomosis  with 
the  terminal  branch  of  the  third  pedal  nerve,  ^e,  which,  it  will  be 
remembered,  sends  a  branch  to  the  anterior  face  of  the  Organ  of 
Bohadsch,  and  one  uniting  with  the  vulvar  nerve  from  the  right 
parietal  ganglion.     By  this  arrangement  the  hypobranchial  gland 
receives  its  nerve  supply  not  only  from  the  right  pedal  ganglion, 
but  also  from  the  left  visceral  one  as  well.    It  would  be  an  inter- 
esting physiological  problem  to  determine  the  relative  influence 
of  these  two  nerves  with  such  different  origins  upon  the  secretory 
activity  of  the  gland.    Mazzarelli  ('90)  has  made  a  comparative 
study  of  the  morphology  of  the  gland  of  Bohadsch  in  a  number 
of  Aplysiidae,  and  has   represented   diagramatically  the   inner- 
vation  in  seven  species.    In  all  of  these  the  nerve  supply  is  found 
to  be  from  the  right  pedal  ganglion,  but  in  none  of  them  is  any 
mention  made  of  such  relations  as  are  here  described  for  the  two 
Brazilian  species.    In  figs.  36  and  37  of  Plate  IX  I  have  repro- 
duced Mazzarelli's  figures  17  and  19  of  Tav.  I  for  Tethys  punctata 


C4  OPISTHOBRANCHIATA   OF   BRAZIL 

and  Tethys  depilans  as  typical  of  his  results.  In  figs.  38  and  39  of 
the  same  plate  I  have  made  similar  diagrams  showing  the  innerva- 
tion  for  Tethys  dactylomela  and  Tethys  cervina,  according  to  my 
dissections.  Vayssiere  ('85)  describes  and  figures  for  Tethys 
depilans  a  branch  of  the  "nerf  genital,"  which  originates  from  the 
left  visceral  ganglion  (not  from  the  right,  as  quoted  by  Mazza- 
relli,  p.  8),  and  passes  to  the  "glande  opaline,"  or  gland  of 
Bohadsch,  as  in  the  forms  here  described.  He  does  not  find,  how- 
ever, the  innervation  from  the  pedal  ganglion  also.  Mazzarelli 
disputes  the  accuracy  of  the  observations  of  Vayssiere,  holding 
that  the  nerve  supply  is  from  the  pedal  ganglion  alone.  In  Tethys 
dactylomela  and  Tethys  cervina  we  have  seen  that  both  ganglia 
in  question  send  nerves  to  the  Organ  of  Bohadsch,  so  in  these 
forms  both  authors  would  be  partly  right,  and  it  would  not  be  a 
matter  of  great  surprise  to  find,  upon  a  reexamination  of  the 
Mediterranean  Aplysiidae  that  in  them  also  the  double  innerva- 
tion actually  exists. 

3.  The  third  nerve  (PI.  VIII,  fig.  35 ;  PI.  X,  fig.  42,  /.  v.  5), 
arises  from  the  posterior  margin  of  the  left  visceral  ganglion  and 
courses  backward,  giving  off  a  slender  branch  to  the  liver,  crosses 
the  large  hermaphroditic  duct  near  its  origin,  sending  a  delicate 
branch  to  it,  swells  into  the  small  genital  ganglion,  (PI.  VIII,  fig. 
35,  g.  £.),  lying  at  the  base  of  the  adnexed  genital  mass,  and 
thence  passes  backward  parallel  to  the  small  hermaphroditic  duct 
for  nearly  one-half  the  length  of  the  latter.    To  this  duct  it  sends 
a  branch  (PI.  VIII,  fig.  35,  v.  ja),  which  passes  backward  along 
its  surface  to  the  ovotestis,  sending  a  few  delicate  branches  to  the 
duct  on  the  way.    The  main  trunk  (PI.  VIII,  fig.  35,  v.  jb),  turns 
abruptly  to  the  right,  leaving  the  hermaphroditic  duct  and,  passing 
backward,  ramifies  in  the  dorsal  body  wall  in  front  of  the  anal 
portion  of  the  alimentary  canal. 

4.  The  fourth  nerve  (PI.  VIII,  fig.  35 ;  PI.  X,  fig.  42,  /.  v.  4), 
equal  in  size  to  the  second  and  third,  arises  at  the  posterior  end 
of  the  ganglion,  close  to  the  base  of  the  third  nerve,  diverges  to 
the  left,  sending  a  branch  to  the  liver,  and  courses  obliquely  across 
below  the  pericardium  to  its  posterior  wall.     A  strong  branch 
(PI.  VIII,  fig.  35,  4a),  is  sent  off  about  midway  of  this  course 
which  ramifies  to  the  ventricle  and  the  pericardial  wall,  the  main 
trunk,  (PI.  VIII,  fig.  35,  ft),  curving  dorsally  in  the  posterior 


TETHYS  CERVINA  DALL  AND  SIMPSON  55 

wall  of  the  pericardium,  bifurcates  to  the  kidney,  the  dorsal  peri- 
cardial  wall  and  the  auricle  near  the  entrance  of  the  branchial  vein. 
In  Tethys  dactylomela  and  in  the  Mediterranean  Aplysiidae 
studied  by  Mazzarelli  ('93,  Monog.  p.  108)  the  third  and  fourth 
nerves,  here  described  as  separate  for  Tethys  cervina,  are  united 
in  one  trunk  for  some  distance  from  their  origin. 

THE  REPRODUCTIVE  SYSTEM. 

The  ovotestis  (PI.  VI,  fig.  33,  ov.  t.)  is  an  irregular  lobulate 
organ,  situated  at  the  posterior  end  of  the  visceral  mass,  closely 
united  to  the  liver  in  front,  and  inclosed  in  the  last  turns  of  the 
intestine.  From  its  median  antero-dorsal  face  the  small  herma- 
phroditic duct  (PI.  VI,  fig.  33,  sm.  h.  d.)  arises,  a  white  nearly 
straight  tube,  9.0  mm.  in  length,  gradually  increasing  in  diameter 
from  0.3  mm.  as  it  emerges  from  the  ovotestis,  to  0.8  mm.  near  the 
adnexed  genital  mass.  The  adnexed  genital  mass  is  a  flattened, 
elliptical  complex,  made  up  of  the  nidamental  and  albumen  glands 
and  the  fertilization  chamber,  inclosed  in  the  loops  of  the  genital 
duct,  (fig.  33,  sp.  p.,  c.  p.),  and  is  situated  immediately 
behind  and  below  the  right  posterior  border  of  the  pericardium. 
It  is  2.0  mm.  in  length,  1.3  mm.  in  greatest  width,  and  i.o  mm.  in 
thickness.  Its  position  is  in  almost  direct  prolongation  of  the 
large  hermaphroditic  duct,  which  extends  forward  along  the  right 
body  wall  to  the  external  opening.  At  the  left  of  its  basal  end 
the  spermatocyst  (PI.  VI,  fig.  33,  sp.  c.)  projects  transversely  as 
a  free  pear-shaped  sack,  its  length,  i.o  mm.,  being  one-half  the 
length  of  the  adnexed  genital  mass,  while  its  diameter  is  nearly 
0.5  mm.  Its  duct  (PI.  VI,  fig.  33,  d.  C.},  the  "duct  of  Cuvier," 
opens  into  the  proximal  end  of  the  copulatory  duct  (PI.  VI,  fig.  33, 
cop.  d.).  The  stout  large  hermaphroditic  duct  is  4.5  mm.  in 
length,  one-half  that  of  the  small  hermaphroditic  duct,  its  diam- 
eter i.o  mm.  being  practically  the  same  throughout.  It  is  made 
up  of  two  channels,  separated  by  deep  folds  of  the  dorsal  and 
ventral  walls,  which  overlap  in  the  median  line  thus  forming  the 
ovo-spermatic  duct  (PI.  VI,  fig.  33,  ov.  sp.  d.)  and  the  copulatory 
duct  (PI.  VI,  fig.  33,  cop.  d.).  At  its  distal  end  it  is  slightly 
enlarged  and  receives  the  long  slender  duct  of  the  vesicle  of 
Swammerdam,  the  spermatotheca,  (PI.  VI,  fig.  33,  spth.},  which 
enters  from  the  left  side  and  above.  This  duct  is  3.0  mm.  long 


tjg  OPISTHOBRANCHIATA   OF   BRAZIL 

and  o.i  mm.  in  diameter.  The  spermatotheca  is  thin  walled, 
spherical  and  i.o  mm.  in  diameter.  A  very  slightly  developed 
system  of  folds  in  the  wall  of  the  large  hermaphroditic  duct, 
close  to  and  above  its  external  opening,  probably  functions  as  a 
vulvar  gland. 

The  spermatic  portion  of  the  duct  is  continued  forward 
beyond  the  external  opening  as  a  deep  groove  along  the  side  of 
the  animal,  downward  and  forward,  to  the  penis  opening,  sit- 
uated as  usual  on  the  right  side  of  the  head,  just  below  the 
anterior  tentacle.  The  penis  is  inclosed  in  an  evertible,  muscular 
sack,  the  posterior  end  of  which  is  attached  to  the  foot  and  the 
lower  body  wall  by  two  groups  of  retractor  muscles,  a  dorsal  and 
a  ventral  set.  The  spermatic  groove  is  continued  along  the  inner 
wall  of  this  sheath  to  its  base,  where  the  penis  proper  is  attached, 
and  is  thence  continued  forward  along  the  side  of  that  organ  to 
its  tip.  In  its  retracted  condition  the  penis  sack  measures  7.0  mm. 
Its  inner  wall  is  thrown  into  a  series  of  longitudinal  folds,  between 
two  of  which  the  spermatic  groove  is  inclosed.  This  and  the 
adjacent  folds  are  sprinkled  with  brown  pigment. 

The  proximal  end  of  the  sheath  is  occupied  by  the  retracted 
penis,  a  slightly  flattened,  conical,  muscular  organ,  0.6  mm.  in 
diameter  at  the  base,  and  ca.  2.5  mm.  long  in  its  retracted  con- 
dition. Along  its  whole  length  extends  a  deep  furrow,  the 
spermatic  groove,  continuous  at  its  base  with  the  groove  upon  the 
inner  surface  of  its  sheath.  No  trace  can  be  made  out  of  any 
armature  upon  any  portion  of  the  penis  or  its  sheath,  nor  is  there 
any  specialized  glandular  area  present. 

THE  ORGAN  OF  BOHADSCH. 

The  organ  of  Bohadsch,  or  hypobranchial  gland,  is  spherical, 
somewhat  flattened  in  form,  of  a  whitish  color,  and  has  a  diameter 
of  4.0  mm.  In  general  aspect  it  presents  the  appearance  of  a 
close  bunch  of  grapes,  its  surface  being  nodular  in  form,  corre- 
sponding to  the  very  large  gland  cells  of  which  it  is  constituted. 
The  gland  opens  externally  by  a  single  large  duct,  the  orifice 
with  tumid  margins  being  situated  upon  a  conspicuous  elevation 
below  the  ctenidium  and  behind  the  reproductive  opening. 

Large  gland  cells  similar  in  form  to  those  of  the  hypo- 
branchial  gland  are  also  found  scattered  in  the  mantle  margin, 


TETHYS  CERVINA  DALL  AND  SIMPSON  57 

and  doubtless  contribute  to  the  well  known  characteristic  de- 
fensive secretion  of  these  animals. 

CIRCULATORY,  EXCRETORY  AND  RESPIRATORY  SYSTEMS. 

The  circulatory,  excretory  and  respiratory  systems  of  Tethys 
cervina,  so  far  as  studied,  were  not  found  to  differ  markedly  from 
those  of  other  species,  and  matters  of  familiar  knowledge,  and 
hence  they  will  not  be  entered  upon  in  this  place. 

Leland  Stanford  Junior  Zoological  Museum,  Invertebrate 
Series  No.  144. 


TRIBE  III.    PLEUROBRANCHOIDEA. 

Dorsal  region  covered  by  a  large  shield-like  mantle,  or 
notaeum.  Shell  external,  internal  or  absent.  Head  distinct,  with 
two  pairs  of  tentacles.  A  single  ctenidium  on  the  right  side, 
between  the  mantle  and  foot.  Foot  without  parapodia.  Genital 
duct  diaulic,  the  male  and  female  apertures  contiguous.  Visceral 
commissure  short. 

Family  PLEUROBRANCHIDAE. 

Mantle  fleshy,  stiffened  by  spicules,  concealing  wholly  or 
partly  the  delicate  haliotiform  shell,  if  developed  at  all.  Anterior 
tentacles  united  to  form  a  frontal  veil,  posterior  tentacles,  or 
rhinophores,  auriculate.  Foot  flattened,  large.  Radula  multiserial, 
with  no  rhachidian  teeth.  Mandibles  well  developed,  composed 
of  many  oblong  plates  arranged  in  tesselated  pattern. 

Genus  PLEUROBRANCHUS  Cuvier,  1805. 

Pleurobranchus,  Cuvier.  Memoire  sur  la  Phyllidie  et  sur  le 
Pleurobranche.  Annales  du  Museum  d'Histoire  Na- 
turelle,  V,  1805,  p.  266-276,  PI.  18,  Figs.  1-6. 

Berthella,  Blainville.  Manuel  de  Malacologie.  1825,  p.  460,  627, 
PI.  XLIII,  Fig.  i. 

Pleurobranchus,  Pilsbry.  Tryon's  Manual  of  Conchology,  XVI, 
1896,  p.  191. 

Pleurobranchus,  Vayssiere.  Monographic  des  Pleurobranchides. 
Ann.  des  Sciences  Naturelles,  Zoologie.  Ser  8,  T.  VIII, 
1898,  p.  279. 

Pleurobranchus,  Bergh.  Malacologische  Untersuchungen,  IV. 
i,  3,  in  Semper's  Reisen  im  Archipel  der  Philippines 
VII,  1898,  p.  117. 

Body  elliptical,  mantle  more  or  less  developed,  its  borders 
free,  the  anterior  border  more  or  less  emarginate ;  shell  internal, 
calcareous  or  subcalcareous.  Rhachis  of  ctenidium  smooth.  Male 
and  female  genital  openings  contiguous,  or  almost  united.  Mandi- 
bles made  up  of  flattened,  closely  set  elements. 


PLEUROBRANCHUS    AGASSIZII    MAC  FARLAND  59 

Pleurobranchus  agassizii  Sp.  Nov. 
Plates  XI  and  XII,  Figs.  43-57. 

Three  small  specimens  of  a  Pleurobranchus  were  taken  by 
Mr.  Greeley  at  Riacho  Doce,  Alagoas.  They  were  killed  in 
formalin  and  afterward  transferred  to  alcohol.  The  coloration 
of  the  animals  in  life  was  not  noted;  the  color  of  the  preserved 
specimens  is  a  rather  uniform  pale,  pinkish  yellow.  In  two  of  the 
specimens  a  fine  light  brown  mottling  seemed  to  divide  the  dorsum 
into  very  minute  polygonal  areas,  but  even  this  trace  of  color 
gradually  disappeared  on  their  being  transferred  to  alcohol. 

EXTERNAL  CHARACTERS. 

Size.  The  three  individuals  measured  10,  n  and  8  mm.  in 
total  length,  by  6,  6.5  and  5.0  mm.  in  width  respectively.  In  each 
case  the  foot  is  somewhat  contracted,  the  mantle  but  slightly  so, 
the  measurements  in  life  probably  exceeding  the  above  somewhat. 
The  length  of  the  foot  is  6.5,  6.0  and  5.5  mm.,  with  corresponding 
widths  of  4.0,  4.0  and  3.0  mm.  in  each  case. 

Body  form.  The  body  is  arched,  slightly  depressed,  oblong; 
the  mantle  broad,  extending  far  beyond  the  foot  throughout  its 
entire  circumference,  though  the  strongly  contracted  posterior 
end  of  the  foot,  the  rhinophores,  and  the  frontal  veil  probably 
extend  well  beyond  the  mantle  margin  in  the  living  animal.  The 
mantle  margin  is  very  slightly  emarginate  above  the  tail.  The 
surface  of  the  dorsum  is  smooth,  save  for  slight,  irregular  nodo- 
sities formed  by  unequal  contraction.  The  mantle  margin  is 
moderately  thick  and  very  wide,  being  2.0  mm.  in  width,  its  free 
edge  being  smooth. 

Shell  The  white  calcareous  shell  (PI.  XI,  fig.  43)  shows 
plainly  through  the  mantle  in  all  the  specimens.  It  is  placed  well 
forward,  its  anterior  margin  being  above  the  head  region,  while 
the  posterior  portion  covers  the  anterior  two-thirds  of  the  poste- 
rior visceral  mass.  In  outline  it  is  oblong,  nearly  linear,  the 
lateral  margins  being  nearly  parallel.  The  anterior  margin  is 
more  gently  rounded  than  the  posterior  one,  the  spire  very  small, 
oblique,  the  whole  shell  being  made  up  of  about  two  turns,  the 
outermost  one  very  broad  and  flat,  and  forming  almost  the  whole 
area  of  the  shell.  The  lines  of  growth  are  plainly  marked ;  the 


60  OPISTHOBRANCHIATA  OF  BRAZIL 

inner  and  outer  surfaces  of  the  shell  are  quite  smooth.  The 
length  of  the  shell  varies  in  the  three  specimens  from  4.2  mm.  to 
5.5  mm.,  its  width  from  2.5  mm.  to  3.0  mm. 

Foot.  The  foot  is  smooth,  truncately  rounded  in  front,  more 
pointed  behind.  No  well  marked  pedal  gland  is  visible  at  its 
posterior  end.  The  lateral  margins  of  the  foot  are  continuous, 
undulating,  the  anterior  margin  bilabiate,  the  lower  lip  much 
thicker  than  the  upper,  which  bears  a  median  notch.  The  dorsal 
surface  of  the  foot  margin  is  smooth,  with  no  visible  pigmenta- 
tion, if  any  existed  during  life. 

Head.  The  frontal  veil  is  large,  trapezoidal,  its  anterior, 
free  margin  smooth,  nearly  straight,  the  outer  angles  very  slightly 
rounded,  the  external  margin  deeply  auriculate.  The  width  of 
the  frontal  veil  in  the  three  specimens  is  4.0,  4.0  and  3.0  mm. 
respectively,  the  length  being  1.5  mm.  in  all.  The  rhinophores 
(PL  XII,  fig.  57)  are  very  large  cylindro-conical  organs,  their 
bases  contiguous,  but  not  fused.  Each  is  made  up  of  a  loosely 
rolled  plate,  the  margins  external,  the  lower  one  overlapping  the 
upper.  The  margins  are  prolonged  at  the  base  into  a  considerable 
flap,  which  is  free.  Just  above  and  external  to  the  base  the  very 
large  eyes  shine  conspicuously  through  the  integument. 

Ctenidium.  The  branchial  plume  lies  on  the  right  side  in 
the  roomy  space  between  foot  and  mantle,  completely  concealed 
by  the  latter.  It  measures  one-half  the  total  length  of  the  body, 
being  5.0  mm.  long  in  the  largest  specimen,  while  in  the  smallest 
one  it  is  but  2.0  mm.,  i.  e.  one-fourth  the  body  length.  The 
posterior  half  of  the  plume  is  free  from  the  body  wall;  the 
rhachis  entirely  smooth.  The  plume  is  bipinnate,  bearing  about 
twelve  pinnules  on  each  side,  arranged  alternately.  The  anal 
opening  is  situated  above  the  posterior  end  of  the  base  of  the 
branchial  plume. 

INTERNAL  ANATOMY. 

Mandibles.  The  labial  armature  is  made  up  of  a  pair  of 
oblong  mandibles  of  a  light  amber  color  in  their  anterior  portion, 
becoming  paler  behind,  borne  upon  the  sides  of  the  buccal  open- 
ing. Their  greatest  length  is  1.215  mm.,  their  width  0.66  mm., 
being  nearly  twice  as  long  as  wide.  The  oblique  anterior  border 
is  slightly  narrower  than  the  more  rounded  posterior  one,  the  dor- 


PLEUROBRANCHUS    AGASSIZII    MAC  FARLAND  6l 

sal  border  is  rounded,  the  ventral  one  is  straight  (PI.  XII,  fig. 
56).  Each  mandible  is  made  up  of  closely  set  chitinous  elements, 
arranged  in  some  72  transverse  rows,  each  row  containing  about 
35  platelets.  The  anterior  portion  of  the  platelets  of  each  row 
overlaps  the  interspaces  between  the  posterior  portions  of  those 
in  the  preceding  series,  thus  giving  a  close,  tesselated  appear- 
ance to  the  whole  mandibular  plate.  The  individual  elements  of 
the  mandible  are  somewhat  trapezoidal  in  form  (PI.  XI,  figs.  44- 
48).  The  anterior  portion  is  prolonged  above  into  a  flattened 
hook,  directed  obliquely  forward  and  upward,  pointed  at  the  tip, 
and  bearing  laterally  three  to  six  strong  denticles.  Immediately 
behind  the  denticles  upon  each  side  is  borne  a  stout  truncated 
lateral  process,  which  is  in  contact  with  the  corresponding 
process  of  the  adjacent  plate  of  either  side.  The  lateral  pro- 
cesses of  a  platelet  are  not,  however,  exactly  opposite  to  each 
other,  the  dorsal  one  being  slightly  behind  its  fellow  of  the  oppo- 
site side  as  a  rule,  thus  causing  a  slight  obliquity  in  the  row  of 
platelets  across  the  mandible  (PI.  XI,  fig.  46).  Toward  the  dorsal 
margin  the  platelets  become  progressively  thinner,  until  at  the 
margin  itself  they  become  flattened  and  scale  like,  the  anterior 
hook  and  the  lateral  processes  are  lost,  and  the  whole  takes  on  a 
simple  lozenge  shape.  The  body  of  a  typical  platelet  is  thick, 
truncate  posteriorly,  and  fits  closely  in  with  its  fellows.  A  deep, 
narrow,  median  slit  (PI.  XI,  figs.  45,  46)  bifurcates  the  ventral 
surface  of  the  body  of  the  platelet,  extending  backward  nearly 
or  fully  one-half  of  its  length,  and  is  slightly  dilated  posteriorly. 
It  does  not  extend  through  to  the  dorsal  surface,  but  may  be 
readily  seen  from  above  by  a  slight  change  of  focus.  This  groove 
is  well  marked  in  all  except  the  very  youngest  platelets,  its  loca- 
tion in  these  latter  being  overlapped  by  a  granular  mass,  identified 
by  Vayssiere  as  the  remnants  of  the  nucleus  of  the  cell  which 
generated  the  platelet. 

The  dimensions  of  these  elements  varies  from  the  anterior 
to  the  posterior  ends  of  each  mandible,  and  from  end  to  end  of 
each  transverse  row.  The  length  of  a  typical  older  platelet  is 
0.022  mm.,  its  thickness  0.015  mm.,  and  its  width,  inclusive  of 
the  lateral  processes,  0.017  mm.  At  the  posterior  end  of  the 
mandible  the  length  of  a  similarly  situated  platelet  is  0.035  mm-> 
and  its  width  0.019  mm. 


62  OPISTHOBRANCHIATA   OF  BRAZIL 

Radula.  The  radula  is  nearly  colorless,  about  one  and  one- 
half  times  as  long  as  broad.  The  rhachis  is  narrow  and  naked, 
the  lateral  teeth  are  unciform,  strongly  hooked,  and  arranged 
in  48  rows,  with  from  42  to  50  teeth  in  each  half  row.  The  dental 
formula  may  hence  be  expressed  as  42-50  :o  :42-5ox48.  The  inner- 
most tooth  in  each  row  (PI.  XI,  fig.  52)  is  somewhat  smaller 
than  its  neighbors,  the  remaining  teeth  being  approximately  of 
the  same  size,  with  the  exception  of  the  outermost  ones,  which 
decrease  gradually  in  size,  the  last  ones  of  the  series  becoming 
flattened  and  almost  rudimentary  (PL  XI,  fig.  49).  The  body  of 
each  tooth  (PL  XI,  figs.  50-52)  is  oblong,  flattened,  slightly 
oblique,  its  posterior  end  truncate,  in  some  cases  emarginate  or 
notched.  The  anterior  end  is  rounded,  the  inner  margin  expanded 
into  a  flattened  wing,  which  is  overlapped  by  the  next  inner 
tooth,  the  outer  margin  being  nearly  straight.  Viewed  from  below 
(PL  XI,  fig.  53)  the  bases  are  of  a  somewhat  oval  outline,  becom- 
ing more  linear  toward  the  ends  of  the  rows.  A  typical  tooth, 
such  as  the  one  shown  in  side  view  in  PL  XI,  fig.  50,  taken  from 
the  middle  of  the  22d  row,  measures  0.025  mm.  in  total  length 
of  base,  the  height  of  the  hook  above  the  bottom  of  the  base  is 
0.014  mm.  The  outermost  tooth,  such  as  is  shown  in  fig.  49,  of 
PL  XI,  taken  from  the  nth  row,  is  o.oi  mm.  in  base  length,  its 
total  height  being  0.006  mm. 

Viscera.  The  very  poor  preservation  of  the  viscera  pre- 
cluded any  satisfactory  study  of  their  structure  and  relations, 
their  hard  and  brittle  condition  resisting  all  attempts  at  softening. 

NERVOUS  SYSTEM. 

Central  ganglia.  The  central  nervous  system  is  enveloped 
in  a  closely  fitting  connective  tissue  capsule,  very  difficult  to 
remove,  which  also  binds  it  closely  to  the  buccal  mass.  The 
cerebro-pleural  complex  (PL  XII,  fig.  55)  is  closely  fused,  and  the 
two  sides  are  in  such  close  contact  in  the  median  line  that  no 
commissures  connecting  them  may  be  made  out.  No  distinct 
line  of  demarcation  can  be  made  out  between  the  cerebral  and 
pleural  moieties  of  the  complex  upon  either  side,  nor  is  there  any 
grouping  of  the  nerve  cells  to  correspond  to  such  a  division, 
ine  separation  into  two  distinct  ganglia  as  shown  by  Von 
Ihermg  ('77)  for  PI  meckeH  (fig>  8>  Taf  n 


PLEUROBRANCHUS    AGASSIZII    MAC  FARLAND  63 

obtain,  the  two  ganglia  being  united  into  a  single  flattened  mass, 
circular  in  outline,  and  having  a  diameter  of  0.36  mm.  The 
pedal  ganglia  are  slightly  smaller  than  the  cerebro-pleural  ones, 
being  0.3  mm.  in  diameter,  and  having  the  same  flattened, 
spherical  form.  The  eyes  are  very  large,  nearly  spherical  struc- 
tures, 0.15  mm.  in  diameter,  and  borne  upon  very  short  optic 
nerves. 

Connectives.  The  cerebro-pedal  and  pleuro-pedal  connectives 
(PI.  XII,  fig.  55,  c.  p.  con.,  pi  p.  con.)  are  extremely  short  and  can 
only  be  seen  after  carefully  dissecting  away  the  capsule  and  dis- 
placing the  ganglia  by  gentle  pressure  upon  the  cover  glass. 

Otocysts.  The  otocysts,  not  represented  in  fig.  55  of  PL  XII, 
are  spherical  structures,  0.06  mm.  in  diameter.  They  are  situated 
at  the  upper  inner  border  of  the  inner  face  of  the  pedal  ganglia, 
close  to  the  cerebro-pedal  connectives,  and  contain  a  large  num- 
ber of  minute  otoconia. 

REPRODUCTIVE  SYSTEM. 

The  glans  penis  is  extruded  in  all  three  specimens.  It  is 
short  and  bluntly  conical,  and  is  surrounded  at  its  base  by  a  con- 
spicuous fold  of  integument,  which  is  continuous  all  around  save 
at  the  posterior  side,  where  its  ends  overlap  with  a  deep  fissure 
between  them.  Just  within  this  fissure,  and  close  to  the  posterior 
portion  of  the  base  of  the  glans  penis  is  the  female  opening  (PI. 
XI,  fig.  54,  v).  The  exact  relations  of  this  opening  with  that 
of  the  duct  of  the  nidamental-albumen  gland  could  not  be  made 
out  satisfactorily.  They  are  very  close  together,  the  gland  duct 
seeming  to  have  a  common  external  opening  with  the  vagina, 
but  the  condition  of  the  material  made  this  and  other  points  in 
the  structure  of  the  reproductive  system  uncertain.  In  sections 
the  glans  penis  is  circular,  and  there  is  no  indication  of  an 
anterior  wing-like  appendage,  such  as  is  given  by  Vayssiere  as  a 
characteristic  of  his  subgenus  Pleurobranchus  s.  str.  (Monog. 
'98,  p.  307). 

SYSTEMATIC  POSITION. 

There  can  be  no  doubt  but  that  this  species  is  distinct  from 
the  three  Antillean  forms  described  by  Morch  ('63),  especially 
in  the  light  of  the  careful  anatomical  description  which  Bergh 


64  OPISTHOBRANCHIATA   OF   BRAZIL 


('97,  'pSb)  has  given  of  these  forms.  Its  lack  of  agreement 
with  Pleurobranchus  patagonicus  d'Orbigny,  the  only  recorded 
species  from  the  east  coast  of  South  America,  is  equally  clear  from 
Bergh's  study  of  the  anatomy  of  that  species  ('pSa).  Nor  does 
it  agree  satisfactorily  with  the  Antillean  Pleurobranchus  lacteus 
of  Dall  and  Simpson  ('99,  p.  367)  in  external  characters  nor  in 
shell.  An  anatomical  study  of  the  latter  species  is  much  to  be 
desired,  however,  before  certainty  can  be  assured.  In  the  mean- 
time I  must  consider  the  present  form  a  new  species  and  have 
much  pleasure  in  dedicating  it  to  Professor  Alexander  Agassiz 
of  Harvard  University. 

Type  No.  145,  Invertebrate  Series,  Leland  Stanford  Junior 
University  Zoological  Museum. 


SUBORDER  NUDIBRANCHIATA. 

Naked  hermaphroditic  opisthobranchiate  Mollusca,  gener- 
ally of  symmetrical,  slug-like  form;  without  a  shell  in  the  adult 
state.  Ctenidium  and  osphradium  absent;  symmetrical  accessory 
respiratory  appendages  usually  developed  from  the  dorsal  integu- 
ment, rarely  from  the  sides.  Central  nervous  system  concentrated. 
Radula  usually  strong,  the  teeth  uni-  or  multiserial.  Kidney  not 
compact. 

TRIBE  I.     DORIDOIDEA. 

Genital  duct  triaulic,  liver  completely  inclosed  in  the  visceral 
mass,  female  duct  bifurcated.  Anal  aperture  postero-median 
upon  the  dorsum,  surrounded  by  the  branchial  rosette,  or  rarely 
between  the  perinotaeum  and  the  foot. 

Family  DORIDIDAE. 

Branchial  plumes  in  an  arc  or  circle,  usually  joined  together 
at  their  bases,  usually  retractile  into  a  common  cavity.  Rhino- 
phores  always  with  perfoliate  clavus.  Pharyngeal  bulb  never 
suctorial. 

Subfamily  DISCODORIDINAE. 

Body  not  hard,  depressed;  the  dorsum  minutely  granu- 
ligerous.  Mantle  margin  rather  wide;  tentacles  digitiform; 
branchial  plumes  usually  tri-  or  quadripinnate ;  foot  rather  wide. 

Labial  armature  made  up  of  minute,  closely  set  rods.  Rha- 
chis  of  radula  naked,  the  pleurae  multidentate,  the  teeth  hooked. 

Penis  usually  unarmed. 

Three  specimens  of  Dorididae  were  found  in  the  collection, 
all  of  them  being  apparently  new  species. 


Genus  DISCODORIS,  Bergh,  1877. 

Discodoris  Bergh.  Jahrbiicher  der  deutschen  Malakozoo 
logischen  Gesellschaft,  IV,  1877,  p.  61.  — Malacologische 
Untersuchungen,  XII,  1877,  p.  518.  —Mai.  Unters. 
XV,  1884,  p.  658.  —Mai.  Unters.  Supplement  Heft  I, 
1880,  p.  47:  II,  1881,  p.  108.  —Mai.  Unters.  XVII,  1890, 
p  895.  — System  der  Nudibranchiaten  Gasteropoden. 
1892,  p.  102.  — Challenger  Reports,  X,  1884,  p.  92. 
—Die  Opisthobranchiata  der  Siboga  Expedition.  1905, 
p.  98. 

Body  rather  soft,   rounded  or  oval   in   outline;   branchial 
aperture  slightly  crenulate,  stellate  or  bilabiate ;  the  anterior  mar- 
gin of  the  foot  bilabiate,  the  upper  lip  more  or  less  notched. 
Prostate  gland  large. 

Discodoris  branneri  Sp.  Nov. 

Plate  XII,  figs.  58-65. 

One  specimen  of  this  form  was  taken  at  Riacho  Doce, 
Alagoas,  and  was  preserved  in  formalin,  followed  by  alcohol. 
The  rhinophores  and  branchiae  are  completely  retracted,  the 
whole  specimen  being  slightly  contracted  and  rolled  up.  No 
notes  accompanied  it  save  that  of  locality  alone. 

EXTERNAL  CHARACTERS. 

Form.  Color.  The  body  is  depressed,  linear  oblong  with 
bluntly  rounded  anterior  and  posterior  ends.  The  dorsum  is 
minutely  villous,  being  everywhere  covered  with  minute  conical 
papillae.  The  mantle  edge  is  thin  and  broad,  extending  far 
beyond  the  margin  of  the  foot,  and  is  fully  one-half  the  width 
of  the  latter  in  the  preserved  specimen.  The  general  ground 
color  of  the  dorsum  is  pinkish,  with  thickly  scattered  irregular 
blotches  of  brown  everywhere  over  its  surface.  Along  the  sides 
of  the  dorsum  is  a  longitudinal  row  of  five  or  six  larger  black 
spots  about  equidistant  from  each  other. 

Foot.  The  foot  is  smooth,  almost  linear,  its  anterior  and 
posterior  ends  bluntly  rounded.  The  anterior  margin  of  the 
foot  is  thickened,  and  deeply  bilabiate,  the  upper  lip  bilobed  by 


PLEUROBRANCHUS    AGASSIZII    MAC  FARLAND  67 

a  deep  median  notch.  Its  length  is  24.0  mm.,  the  width  12.0  mm. 
The  ground  color  of  the  foot  is  pinkish,  thickly  set  with  irregular 
brownish  blotches,  apparently  arranged  at  random,  i.  e.  producing 
no  definite  color  pattern.  The  largest  of  these  blotches  may 
reach  a  diameter  of  i.o  mm.,  but  the  majority  are  much  smaller. 

Head.  The  head  is  retracted  and  bears  two  tapering 
conical  oral  tentacles,  2.5  mm.  long,  and  with  a  basal  diameter  of 
i.o  mm. 

Rhinophores.  The  rhinophores  are  completely  retracted 
within  their  sheaths,  the  margins  of  which  are  low  and  closely 
set  with  short  slender  papillae.  The  clavus  of  the  rhinophore  is 
stout,  club  shaped,  and  lamellate. 

Branchiae.  The  branchiae  are  situated  as  usual  upon  the 
posterior  mid-dorsal  region,  surrounding  the  anal  papilla  and  the 
renal  opening.  They  are  six  in  number,  tripinnate,  and  retractile 
within  a  deep  branchial  pocket,  the  margin  of  which  is  thin  and 
slightly  prominent. 

Total  length  of  the  specimen  32.0  mm.,  its  width  12.0  mm. 

INTERNAL  ANATOMY. 

The  dorsal  wall  of  the  body  cavity  is  rather  firm  and  thick, 
its  peritoneal  lining  colorless,  save  for  a  pinkish  tint,  which  is 
possessed  by  all  the  viscera  in  common. 

ALIMENTARY  SYSTEM. 

The  alimentary  canal  is  of  the  general  type  of  the  crypto- 
branchiate  Dorids.  The  pharyngeal  bulb  is  conical,  truncate  in 
front,  3.5  mm.  long,  by  2.5  mm.  wide,  and  3.0  mm.  in  height,  the 
radula  sheath  projecting  behind  and  below  as  a  rounded  eminence. 
The  mouth  opening  is  of  an  inverted  T  shape,  the  labial  disc 
being  covered  by  a  firm  transparent  cuticle. 

Labial  armature.  Externally  the  opening  is  guarded  on 
either  side  by  a  somewhat  triangular,  yellow  plate,  the  apex  of 
which  is  directed  backward  (PI.  XII,  fig.  58).  The  anterior 
border  of  each  of  these  labial  plates  is  slightly  convex,  ca.  0.81  mm. 
long,  the  upper  border  is  straight,  0.72  mm.  long,  and  is  separated 
from  its  fellow  on  the  opposite  side  by  a  distance  of  from  0.05  to 
0.06  mm.  The  posterior  border  is  very  slightly  concave,  1 .08  mm. 
in  length,  while  the  lower  angle  is  rounded. 


68  OPISTHOBRANCHIATA   OF   BRAZIL 

These  mandibular  plates  are  made  up  of  slender  closely 
set  blunt  rodlets,  longest  in  front  and  decreasing  in  length  toward 
the  posterior  border.  Those  of  the  anterior  portion  range  up  to 
0.096  mm.  in  length  (PI.  XII,  fig.  59),  and  decrease  regularly 
toward  the  posterior  portion,  where  they  are  very  short  (PI.  XII, 
fig.  60),  the  average  diameter  of  ca.  0.005  mm.  remaining  nearly 
the  same  throughout,  the  tips  of  the  rodlets  being  slightly  dilated 
to  nearly  the  same  extent  also. 

Radula.  The  radula  is  broad  and  short,  deeply  grooved 
longitudinally  in  the  median  line,  the  teeth  of  one  sort,  uniform 
in  shape,  strongly  hooked,  and  arranged  in  26  rows  of  from  45 
to  48  teeth  in  each  half  row,  the  rhachis  being  destitute  of  teeth. 
The  dental  formula  may  hence  be  expressed  as  45-48  :o  :45~48x26. 
The  outermost  two  or  three  teeth  of  each  row  (PI.  XII,  fig.  62) 
are  slightly  smaller  than  the  remaining  teeth  of  the  row,  the  base 
of  the  outermost  being  about  one-third  the  length  of  that  of  the 
others,  the  remaining  teeth  being  practically  of  the  same  size 
until  the  innermost  two  are  reached,  which  are  again  somewhat 
smaller.  The  average  height  of  a  typical  tooth  (PI.  XII,  fig.  63) 
is  0.186  mm.,  the  length  of  the  base  0.15  mm.  The  general  tint 
of  the  radula  is  a  faint  yellow,  deepening  posteriorly,  while  the 
anterior  portion  is  colorless  or  nearly  so. 

Blood  gland.  Overlying  the  buccal  mass  is  the  blood  gland, 
divided  into  two  lobes,  the  largest  being  thick  and  rounded,  about 
2.0  mm.  in  diameter,  and  is  situated  in  front  of,  and  in  contact 
with  the  central  nervous  system.  The  posterior  lobe,  immediately 
behind  the  anterior  one,  is  much  smaller,  triangular  in  form,  its 
base  being  directed  forward,  and  has  a  length  of  1.5  mm.  and 
a  breadth  of  0.5  mm.  at  the  broadest  end. 

Salivary  glands.  The  salivary  glands  are  long  and  strap-like, 
the  anterior  portion,  i.o  mm.  in  width,  being  coiled  upon  the 
posterior  face  of  the  pharyngeal  bulb.  Each  narrows  to  0.5  mm. 
in  width  as  it  passes  through  the  nerve  collar,  and  extends  back- 
ward, below  the  viscera  ventrally,  for  about  one-half  the  total 
length  of  the  animal. 

Esophagus,  stomach  and  intestine.  The  esophagus  is  short 
and  wide,  ca.  3.0  mm.  long  by  1.5  mm.  in  diameter,  passing  directly 
downward  and  backward  to  the  stomach,  into  which  it  dilates. 
The  latter  organ  lies  in  a  deep  notch  in  the  anterior  face  of  the 


DISCODORIS    BRANNERI    MAC  FARLAND  69 

posterior  visceral  mass.  It  describes  a  C  shaped  loop  upon  itself, 
the  pyloric  end  lying  almost  directly  above  the  anterior  portion. 
The  anterior  half  of  the  intestine  is  large  and  dilated,  being  about 
1 1.0  mm.  long  by  2.0  mm.  in  diameter.  It  courses  obliquely 
upward  and  backward  in  a  deep  groove  in  the  upper  right  side 
of  the  visceral  mass,  constricts  suddenly  to  0.5  mm.  in  diameter, 
and  continues  for  about  n.o  mm.  to  the  anal  opening,  situated 
at  the  summit  of  the  anal  papilla,  in  the  center  of  the  branchial 
circle. 

Liver.  The  liver  is  of  the  usual  Dorid  form,  bluntly  conical, 
the  apex  lying  posteriorly  beneath  the  branchiae,  the  anterior  end 
divided  by  a  deep  median  groove  into  right  and  left  lobes,  between 
which  the  stomach  is  inclosed.  The  total  length  of  the  liver  is 
12.0  mm.,  its  maximum  diameter  6.5  mm.  The  dorsal  surface  of 
the  organ  is  divided  by  two  transverse  sulci  into  three  nearly 
equal  lobules,  their  surface  being  diversified  by  an  irregular 
system  of  complicated  ridges  and  shallow  grooves. 

REPRODUCTIVE  SYSTEM. 

Hermaphroditic  gland  and  duct.  The  hermaphroditic  gland 
is  relatively  inconspicuous  and  thin,  the  specimen  evidently  not 
having  been  taken  during  its  breeding  season.  It  can  be  dis- 
tinguished with  difficulty  from  the  upper  surface  of  the  liver 
which  it  closely  covers.  From  the  anterior  border  of  its  right 
lobe  it  gives  rise  to  the  long,  narrow,  whitish  hermaphroditic  duct 
(PI.  XII,  fig.  65,  h.  d.)  which  courses  forward  and  downward  for 
a  distance  of  ca.  3.5  mm.,  dilating  into  the  long  white  hermaphro- 
ditic ampulla  (PI.  XII,  fig.  65,  h.  amp.).  This  latter  organ  is  of 
considerable  size,  making  up  a  large  portion  of  the  anterior 
genital  mass.  It  is  10.0  mm.  in  length  by  i.o  mm.  in  diameter, 
and  is  coiled  in  three  to  four  close  loops  upon  the  posterior  and 
outer  face  of  the  anterior  genital  mass.  At  its  anterior  end  it 
divides  at  once  into  the  spermatic  duct  (PI.  XII,  fig.  65,  sp.  rf.)  and 
the  oviduct  (PI.  XII,  fig.  65,  ov.  d.).  The  former  is  very  short, 
passing  almost  at  once  into  the  apex  of  the  heart-shaped  pinkish 
prostate  gland  (PI.  XII,  fig.  65,  pr.  g.),  which  occupies  the  poste- 
rior inner  face  of  the  anterior  genital  mass.  From  a  deep  median 
groove  in  its  posterior  face  arises  the  slender  vas  deferens  (PI. 
XII,  fig.  65,  v.  d.}.  The  total  length  of  the  prostate  gland  is  4.0 


«0  OPISTHOBRANCHIATA   OF   BRAZIL 

mm.,  its  greatest  breadth  3.0  mm.  and  thickness  2.0  mm.  Its 
surface  is  very  finely  tabulated. 

Vas  deferens  and  penis.  The  vas  deferens  courses  straight 
forward  and  outward  along  the  inner  and  anterior  faces  of  the 
complex  to  the  penis.  Throughout  its  whole  length  it  preserves 
a  uniform  diameter  of  0.5  mm.,  dilating  suddenly  at  its  outer 
end  into  the  penis.  The  penis  is  somewhat  contracted  and  nearly 
spherical  in  form,  about  2.25  mm.  in  diameter,  the  large  conical 
glans  (PI.  XII,  fig.  65,  p.)  projecting  externally.  The  latter  is 
bluntly  conical,  its  apex  truncate,  2.0  mm.  in  length,  i.o  mm.  in 
diameter  at  the  base,  and  tapering  to  0.5  mm.  at  the  apex.  The 
glans  bears  an  armature  of  minute  hooks,  set  in  longitudinal 
rows,  about  17  in  number  near  the  distal  end  of  the  glans  and 
increasing  to  nearly  100  toward  the  base.  The  individual  hooks 
(PI.  XII,  fig.  64,  a,  b)  are  rather  stout,  the  largest  occurring  near 
the  base  of  the  glans,  and  measuring  0.02  to  0.027  mm.  in  height, 
their  basal  dimensions  being  nearly  the  same. 

Vagina  and  duct.  The  vagina  and  vaginal  duct  lie  upon  the 
upper  anterior  border  of  the  anterior  genital  complex  (PI.  XII, 
fig.  65,  vag.},  and  are  of  about  equal  length.  The  distal  vaginal 
portion  is  conical,  thick  walled,  with  a  series  of  longitudinal  ridges 
upon  its  external  surface,  separated  by  shallow  grooves,  united 
at  intervals  transversely,  giving  the  surface  a  somewhat  lobulated 
appearance,  which  is  due  to  internal  glandular  structures.  In 
sections  through  the  vagina  and  its  duct  the  wall  is  seen  to  be 
made  up  of  two  conspicuous  layers,  an  outer  muscular  one,  con- 
sisting mainly  of  fibres  arranged  in  a  circular  direction,  and  of 
nearly  uniform  thickness,  throughout  the  whole  length  of  the 
vagina  and  its  duct,  varying  but  slightly  from  about  0.045  mm- 
An  inconspicuous  submucous  layer  of  connective  tissue  bears 
the  innermost  coat,  the  mucous  layer,  which  is  made  up  of  a 
layer  of  columnar  epithelial  cells,  distended  with  secretion  prod- 
ucts. This  mucous  layer  is  thrown  into  closely  crowded  leaf- 
like  longitudinal  folds,  about  twenty  in  number  in  the  proximal 
portion  of  the  vagina,  and  increasing  to  some  fifty  or  more  in  the 
distal  extremity.  These  folds  range  in  height  from  0.09  mm. 
to  0.24  mm.  in  the  proximal  and  distal  portions  respectively.  The 
narrow  central  lumen,  left  free  from  the  folds,  is  filled  with  a 
coagulated  mucous-like  secretion. 


DISCODORIS     BRANNERI     MAC  FARLAND  7! 

The  vaginal  duct  is  whitish,  muscular,  of  nearly  uniform 
diameter,  and  4.0  mm.  in  length.     It  describes  a  loop  (PI  XII  fig 
65)    returning  upon  itself  and  opening  into  the  spermatotheca 
PL    XII,   65,   Spth.},    which   is    a   conspicuous   dark   spherical 
structure,  2.0  mm.  in  diameter,  lying  in  the  mid-dorsal  region  of 
the  anterior  genital  complex.     Upon  its  dorso-anterior  face  is 
the  common  opening  of  the  vaginal  and  the  uterine  ducts    con- 
cealed by  the  overlapping  proximal   end  of  the   vagina  '  The 
uterine  duct  (PI.  XII,  fig.  65,  u.  rf.)  is  slightly  the  more  slender  of 
the  two,  and  passes  obliquely  forward  along  the  inner  face  of 
the  nidamental  gland,  beneath  the  sack  like  spermatocyst,  which 
is  doubled  above  it.     Near  the  anterior  end  of  the  nidamental 
gland  the  uterine   duct  receives  the  short  slender  duct  of  the 
spermatocyst  (PI.  XII,  fig.  65,  sp.  ,.),  an  elongated  pear-shaped 
organ  of  a   whitish   color,    1.5   mm.   in   length   by    i.o  mm.   in 
diameter,  and  closely  packed  with  spermatozoa.    Its  slender  duct 
is  slightly  less  than  one-half  the  length  of  the  cyst  itself 

Nidamental  gland.    The  uterine  duct  passes  into  the  anterior 
id  of  the  nidamental  gland  (PI.  XII,  fig.  65,  ».  a.  c.),  immedi- 
ately after  receiving  the  duct  of  the  spermatocyst,  and  at  a  point 
•   not  far  from  the  entrance  of  the  oviduct,  which  joins  the  anterior 
end   of  the   hermaphroditic   ampulla   to   the   nidamental    gland 
In  most  Dorididae  the  greater  portion  of  the  anterior  genital 
complex  is  made  up  usually  of  the  nidamental  and  the  albumen 
ids.    In  this  individual  the  two  glands  in  question  form  but  a 
very  small  portion  of  the  whole,  being  but  2.0  mm.  in  extreme 
length  by  1.2  mm.  in  width  and   i.o  mm.  in  thickness      This 
proportion  may  possibly  be  due  to  absence  of  secretory  activity 
n  a  non-breeding  season,  or  to  non-maturity.     The  surface  of 
the  nidamental  gland  is  finely  sculptured  with  minute  ridges  and 
ressions,  ,s  pinkish  in  color,  and  opens  externally,  immediately 
dow -and  behind  the  opening  of  the  vagina,  by  means  of  a  broad 
•  XII,  fig.  65,  «.  rf.),  1.5  mm.  in  length.     The  albumen 
gland  is  included  in  the  windings  of  the  nidamental  gland   being 
exposed  as  a  small  oval  area,  i.o  mm.  in  length  by  0.3  mm.  in 
width,  upon  the  upper  face  of  the  larger  gland.    At  the  anterior 
>rder  of  this  area  is  found  the  entrance  of  the  uterine  duct. 

The  systematic  position  of  this  species  presents  some  dif- 
Uties    due   mainly  to   the    well-developed   penis    armature,    a 


72  OPISTHOBRANCHIATA   OF   BRAZIL 

character  not  present  in  the  genus  Discodoris.  In  this  respect 
it  resembles  Carminodoris,  from  which,  however,  it  differs 
strongly  in  other  features,  notably  in  the  granular,  almost  vel- 
vety notaeum.  For  the  present  I  deem  it  best  to  consider  it  a 
species  of  Discodoris  until  the  study  of  further  material  may 
warrant  a  different  disposition,  rather  than  to  create  for  it  a  sep- 
arate genus  based  upon  this  character  alone. 

Some  thirty  or  more  species  of  Discodoris  have  been 
described,  mostly  inhabiting  the  Pacific  and  Indian  oceans.  But 
five  of  these,  D.  notha  Bergh,  D.  muta  Bergh,  D.  indecora  Bergh, 
D.  tristis  Bergh  and  D.  edivardsi  Vayssiere  are  from  the  Atlantic, 
the  first  four  from  the  Antilles,  the  Azores  and  the  Cape  Verd 
Islands,  the  last  from  the  Morocco  coast.  From  all  these  the 
present  species  may  be  distinguished  readily. 

I  take  great  pleasure  in  dedicating  this  new  species  to  my 
esteemed  colleague,  Professor  J.  C.  Branner,  the  originator  and 
leader  of  the  Branner-Agassiz  expedition. 

Type  No.  146  Invertebrate  Series,  Leland  Stanford  Junior 
University  Zoological  Museum. 


Discodoris  voniheringi  Sp.  Nov. 
Plates  XIII,  XIV,  XV;  figs.  66-76. 

One  specimen  of  this  new  species  was  taken  at  Riacho  Doce 
Alagoas,  July  20,  1899,  by  Mr.  Greeley.  No  color  notes  accom- 
panied the  specimen,  which  was  killed  in  formalin,  afterward 
followed  by  alcohol. 

EXTERNAL  CHARACTERS 

Form.  The  general  body  form  is  depressed,  elongate,  ellip- 
tical, the  ends  equally  rounded,  the  mantle  margins  rather  wide 
and  thin,  projecting  far  beyond  the  edge  of  the  foot,  the  sub- 
marginal  space  nearly  equalling  the  width  of  the  foot  itself. 

Color.  The  ground  color  of  the  dorsum  is  pinkish  gray, 
sprinkled  everywhere  with  minute  dark  brown,  or  black  spots' 
The  under  surface  of  the  mantle  and  the  sides  of  the  body  are  a 
lighter  pinkish,  thickly  sprinkled  with  minute  dark  spots,  giving 
the  surface  a  dusty  appearance.  Upon  the  under  surface  of  the 
mantle  on  either  side  is  borne  a  longitudinal  series  of  three  to 
four  large  round  brownish  blotches  about  midway  between  the 
mantle  edge  and  the  sides  of  the  body.  The  largest  of  these  spots 
reaches  a  diameter  of  2.0  mm.  Posteriorly  this  series  is  continued 
around  above  the  top  of  the  foot  by  a  series  of  six  or  seven  much 
smaller  spots  more  irregularly  disposed. 

Dorsum.  The  dorsum  is  rather  firm,  tuberculate,  being 
covered  everywhere  with  low  tubercules  of  varying  size,  inflated 
at  their  tips  and  much  thicker  than  the  slender  cylindro-conical 
processes  covering  the  dorsum  of  the  preceeding  species.  The 
largest  of  these  tubercules  reach  a  diameter  of  i.o  mm.,  and 
occupy  the  summits  of  slight  elevations  of  the  dorsal  integument, 
having  smaller  and  lower  tubercules  irregularly  grouped  around 
them. 

Foot.  The  foot  is  smooth,  rounded  in  front,  its  anterior 
margin  deeply  bilabiate,  the  upper  lip  projecting  beyond  the 
lower,  and  deeply  notched  to  a  depth  of  0.5  mm.  The  sides  of 
the  foot  are  nearly  parallel,  gradually  converging  posteriorly  to 
the  bluntly  rounded  tail,  which  does  not  project  beyond  the 


74 


OPISTHOBRANCHIATA   OF   BRAZIL 


mantle  edge.  The  edges  of  the  foot  are  thin  and  crenulate.  Its 
color  is  in  general  the  same  as  that  of  the  under  surface  of  the 
mantle. 

Head.  The  head  is  inconspicuous,  the  mouth  a  vertical  slit, 
bearing  upon  either  side  long  slender  finger-like  oral  tentacles, 
1.5  mm.  in  length,  their  tips  blunt  and  curving  forward. 

Rhinophores.  The  rhinophores  are  brownish  black,  deeply 
retractile  within  conspicuous  sheaths,  with  high  tuberculate 
margins,  the  tubercules  being  of  the  same  type  as  those  of  the 
general  dorsal  area.  The  sheaths  reach  a  height  of  i.o  mm., 
the  whole  slightly  retracted  rhinophore  has  a  height  of  2.5  mm. 
The  clavus  is  of  the  usual  club  shape,  perfoliate,  with  ca.  25  leaves 
on  each  side.  The  dark  pigment  is  especially  concentrated  on 
the  strong  stalk  of  the  rhinophore,  where  it  forms  a  circular 
band,  immediately  below  the  clavus. 

Branchiae.  The  branchiae  are  six  in  number,  bipinnate, 
completely  retractile  into  the  branchial  pocket,  which  bears  a 
conspicuous  lobulate  margin,  the  low  divisions  of  which  carry 
tubercules  similar  to  those  of  the  dorsum.  The  anal  and  renal 
openings  are  situated  as  usual  within  the  circle  of  the  branchiae. 
The  reproductive  openings  in  the  specimen  were  very  small  and 
inconspicuous. 

Dimensions.  Total  length  of  the  whole  animal  20.0  mm., 
its  width  14.5  mm.,  and  maximum  height  5.0  mm.  Length  of 
the  foot  16.5  mm.,  its  width  6.0  mm.;  greatest  width  of  the 
mantle  margin  6.0  mm. 

INTERNAL  ANATOMY. 

Blood  Glands.  The  dorsal  integument  is  rather  soft  and 
not  thick.  The  pseudo-peritoneum  is  colorless,  save  in  the  region 
of  the  central  nervous  system  where  it  is  thickly  sprinkled  with 
minute,  dark  brown  spots.  The  phagocytic  blood  glands,  two 
in  number  lie  directly  in  contact  with  the  central  nervous  system ; 
the  anterior  larger  one  is  elliptical  in  outline  and  rather  thick, 
measuring  1.5  mm.  in  length  by  i.o  mm.  in  width  and  0.2  mm.  in 
thickness,  and  is  dark  gray  in  color,  being  sprinkled  with  minute 
black  spots.  Its  dorsal  surface  is  arched,  the  ventral  concave, 
while  the  general  contour  is  smooth  throughout.  It  lies  directly 
in  front  of  the  cerebral  ganglia  upon  the  pharyngeal  bulb.  The 


DISCODORIS    BRANNERI     MAC  FARLAND  75 

posterior  lobe  is  very  much  smaller  and  thinner,  and  lies  trans- 
versely, its  anterior  border  in  contact  with  the  central  nervous 
system.  It  is  somewhat  reniform  in  shape,  measuring  0.7  mm 
m  transverse  by  0.3  mm.  in  longitudinal  diameter. 

ALIMENTARY  SYSTEM. 

Labial  armature.  The  oral  tube  is  short  and  conical  i  o 
mm.  in  length,  bearing  a  colorless  cuticula.  The  labial  armature 
is  small,  consisting  of  a  median  plate,  0.735  mm.  in  length  by 
0.135  mm.  in  greatest  width,  and  of  two  triangular  lateral  plates 
0.63  mm.  in  greatest  length  by  0.3  mm.  in  width  (PI.  XIII  fig' 
66).  The  median  plate  is  elongate,  spear-shaped,  and  is  made  up 
of  closely  set  granular  thickenings  of  the  cuticle  of  varying  size 
Its  median  portion  is  marked  by  a  narrow  line  in  which  the 
thickenings  are  much  less  numerous  and  are  smaller  than  on 
either  side.  In  the  densest  regions  these  granulations  may  assume 
the  aspect  of  very  short  blunt  rodlets  measuring  up  to  0002  mm 
in  diameter,  and  approximately  the  same  in  height. 

The  median  plate  is  set  off  from  the  lateral  ones  by  a  narrow 
strip  of  cuticle,  nearly  destitute  of  such  elevations.  The  lateral 
plates  are  approximately  right  angled  triangles  in  general  out- 
lines the  apex  being  directed  backward,  the  perpendicular  side 
parallel  to  the  median  plate.  The  granular  thickenings  forming 
these  lateral  plates  are  of  the  same  general  type  as  those  of  the 
median  one,  are  very  dense  in  the  central  portions  and  merge 
off  gradually  toward  the  periphery  into  the  thickened  cuticula  sur- 
rounding them. 

Radula.  The  pharyngeal  bulb  is  large  and  strong,  3.0  mm.  in 
length  by  2.0  mm.  in  height,  in  form  truncately  conical  the 
radula  sheath  projecting  very  slightly  behind  and  below.  The 
radula  is  broad,  short,  and  deeply  grooved,  colorless  in  front  but 
becoming  straw  colored  posteriorly.  The  teeth  are  in  twenty-six 
rows,  the  rhachis  of  the  radula  is  naked,  and  the  pleural  teeth 
vary  in  number  from  forty-six  in  the  anterior  half  rows  to 
fifty  in  the  posterior  ones.  The  dental  formula  may  be  expressed 
46-50:0:46-50x26.  The  teeth  are  all  simple  hooks  in  form  the 
majority  except  the  outermost  and  innermost  in  each  row  being- 
of  the  same  size  and  shape  (PI.  XIII,  figs.  67,  68;  PI.  XV,  fig.  75) 
The  base  of  a  typical  average  tooth  measures  0.082  mm.,  the  height 


yg  OPISTHOBRANCHIATA   OF   BRAZIL 

0.099  mm.  The  outermost  tooth  in  each  row  is  much  smaller 
than  the  average,  the  base  being  much  shorter,  often  nearly  rudi- 
mentary, and  the  hook  much  more  slender,  as  is  shown  in  the 
slightly  oblique  view  in  fig.  69  of  PI.  XIII.  The  next  two  teeth 
adjacent  to  the  outermost,  are  progressively  larger  and  form  a 
transition  to  the  remainder  in  the  row.  In  like  manner  the  inner- 
most tooth  of  each  row  (PI.  XV,  fig.  76)  is  much  smaller  than  its 
fellows,  the  succeeding  ones  increasing  in  size,  the  typical  dimen- 
sions being  reached  in  the  fifth  or  sixth  tooth  of  each  series. 
In  front  view  all  of  the  teeth  of  the  radula  are  inclined  toward 
the  median  line  by  a  strong  curve  at  their  bases,  the  effect  of 
which  is  partly  nullified  by  a  curve  in  the  reverse  direction  in  the 
middle  and  upper  portion  of  the  shaft  (PI.  XIII,  figs.  67,  68). 

Visceral  complex.  The  esophagus  begins  .with  a  large  dila- 
tion immediately  behind  the  pharyngeal  bulb.  It  recurves  upon 
itself,  narrows,  passes  through  the  commissural  loop  of  the  central 
nervous  system,  and,  after  a  short  course,  opens  into  the  stomach. 
The  posterior  visceral  mass  is  bluntly  conical,  8.0  mm.  long  by 
5.5  mm.  in  maximum  diameter,  its  lateral  and  lower  surfaces 
convex,  the  upper  one  slightly  flattened.  The  upper  anterior  mar- 
gin is  deeply  notched  for  the  reception  of  the  stomach,  the  pyloric 
flexure  of  which  is  uppermost,  passing  gradually  backward  into 
the  wide  intestine,  which  courses  along  the  dorsal  surface  of  the 
liver  to  the  anus.  At  the  left  of  the  pylorus  lies  the  sack-like 
gall  cyst  of  the  liver,  the  greatest  diameter  of  which,  1.4  mm.,  is 
nearly  equal  to  that  of  the  pylorus. 

REPRODUCTIVE  SYSTEM. 

Hermaphroditic  gland  and  duct.  The  hermaphroditic  gland 
lies  as  usual  upon  the  upper  and  anterior  portion  of  the  liver. 
The  slight  development  of  the  reproductive  cells  rendered  this 
gland  relatively  inconspicuous  in  the  specimen.  The  hermaphro- 
ditic duct  is  short  and  slender,  passing  forward  from  the  right 
anterior  lobe  of  the  hermaphroditic  gland,  and,  after  a  course  of 
ca.  1.5  mm.,  dilates  into  the  long  thick  convoluted  hermaphroditic 
ampulla  (PI.  XIV,  figs.  73,  74,  h.  amp.}.  This  is  closely  coiled 
in  a  number  of  loops  upon  the  posterior  and  lower  border  of  the 
anterior  genital  complex,  and  makes  up  fully  one-third  the  bulk 
of  the  latter.  Its  approximate  length  is  7.0  mm.,  with  a  fairly 


DISCODORIS    BRANNERI    MAC  FARLAND  77 

uniform  diameter  of  07  mm.    It  is  grayish  white  in  color,  and  is 
densely  packed  with  spermatozoa. 

The  wall  of  the  hermaphroditic  ampulla  consists  of  a  one- 
layered  low  epithelium,  resting  upon  a  thin  subepithelial  layer 
of  connective  tissue,  which  is  in  turn  enveloped  by  a  thin  non- 
continuous  layer  of  circularly  disposed  smooth  muscle  fibres.  A 
loose  connective  tissue  adventitia,  not  distinctly  separated  from 
the  muscularis,  forms  the  outermost  layer.  In  places  the  whole 
wall  is  so  reduced  in  thickness  that  it  seems  to  be  composed  of 
the  epithelium  alone. 

At  the  rounded  posterior  end  of  the  nidamental  gland  the 
distal  end  of  the  hermaphroditic  duct  passes  into  the  connective 
tissue  along  its  anterior  border,  opening  into  a  rather  large  cavity, 
0.08  mm.  in  diameter,  which  is  continued  forward  in  the  substance 
of  the  gland  for  some  distance.  Immediately  after  entering  the 
nidamental-albumen  gland  complex  the  slender  spermatic  duct  (PI. 
XIV,  figs.  73,  74,  sp.  d.)  is  given  off,  which,  after  its  emergence 
from  the  gland,  passes  almost  immediately  into  the  substance  of 
the  prostate  gland.  These  relations  were  made  out  in  serial 
sections  only,  owing  to  the  minuteness  of  the  structures  involved. 
It  is  of  interest  to  note  that  the  dense  mass  of  spermatozoa,  with 
which  the  hermaphroditic  ampulla  was  filled,  did  not  extend  into 
the  spermatic  duct  at  all,  but  were  confined  to  the  extension  of 
the  ampulla  into  the  nidamental-albumen  gland  complex. 

Prostate  gland.  The  prostate  gland  envelopes  a  U  shaped 
loop  of  the  vas  deferens  (PI.  XIV,  figs.  73  and  74,  pr.  g.).  It  is 
2.0  mm.  in  length,  i.o  mm.  wide,  somewhat  prismatic  in  form, 
approximately  triangular  in  cross  section,  its  surface  smooth  and 
marked  off  into  small  lobules.  Its  posterior  inner  margin  is 
curved,  its  inner  and  ventral  surface  convex,  while  its  anterior 
distal  portion  is  prolonged  into  two  pointed  lobes  which  inclose 
a  portion  of  the  spermatotheca.  It  is  enveloped  by  a  very  delicate 
capsule  of  connective  tissue  covering  the  closely  packed  lobules 
of  the  gland.  The  lumen  is  a  more  or  less  U  shaped  cavity,  the 
walls  of  which  are  formed  by  a  single  layer  of  cubical  to  columnar, 
ciliated  cells,  passing  over  at  the  upper  extremities  of  the  U  into 
the  ciliated  columnar  epithelium  of  the  vas  deferens,  and  the 
spermatic  duct  respectively.  Into  this  cavity  open  at  intervals  the 
very  short  branched  tubular  glands  which  make  up  the  bulk  of 


j7g  OPISTHOBRANCHIATA  OF   BRAZIL 

the  organ.  The  gland  cells  are  large  and  clear,  with  large, 
deeply  staining  nuclei,  the  reticular  cytoplasm  being  distended 
with  a  clear  albuminous  secretion,  staining  with  difficulty.  The 
poor  fixation  of  the  single  specimen  available  precluded  any 
satisfactory  cytological  study  of  the  gland. 

Vas  deferens  and  penis.  From  the  distal  end  of  the  prostate 
gland  passes  the  vas  deferens  (PI.  XIV,  figs.  73, 74,  v.  d.)  a  slender 
tube,  ca.  3.0  mm.  long,  which  courses  with  but  few  loopings 
outward  and  forward,  terminating  in  the  penis  into  which  it  rather 
suddenly  dilates  (PI.  XIV,  figs.  73,  74,  p.).  It  is  lined  with  a 
single  layer  of  slender  columnar  epithelium,  surrounded  by  a  thin 
layer  of  smooth  muscle  cells  and  a  connective  tissue  adventitia. 
Toward  the  distal  end  the  muscular  elements  become  much  in- 
creased, the  wall  of  the  praeputium  being  made  up  almost  entirely 
of  them.  The  penis  was  strongly  retracted  and  curved  upon  itself, 
as  was  also  the  whole  organ.  It  is  bluntly  cylindrical  in  shape, 
slightly  tapering  and  is  entirely  destitute  of  any  armature. 

Vagina.  The  vagina  (PI.  XIV,  figs.  73,  74,  vag.)  is  small 
and  conical  in  general  form,  its  length  in  the  slightly  contracted 
condition  being  i.o  mm.,  with  a  maximum  diameter  of  0.5  mm. 
Its  slender  duct  (PI.  XIV,  fig.  74,  vag.  d.)  passes  directly 
inward  to  the  central  region  of  the  dorsal  face  of  the  anterior 
genital  complex  where  it  opens  into  the  spermatotheca  (PI.  XIV, 
fig.  74,  spth.}.  In  cross  section  about  midway  of  its  length  it 
has  a  diameter  of  0.097  mm->  of  which  0.052  mm.  is  occupied  by 
the  lumen.  The  lining  is  formed  by  a  single  layer  of  cubical 
epithelium  bearing  long  cilia,  in  the  distal  portion  elevated  into 
long  ridges,  which  become  lower  and  disappear  in  the  proximal 
portion.  The  muscular  coat  is  strongly  developed,  and  consists 
of  a  circular  and  a  longitudinal  layer,  enclosed  externally  by  a 
connective  tissue  adventitia. 

Spermatotheca  and  spermatocyst.  The  oblong  flattened 
spermatotheca  lies  in  the  center  of  the  dorsal  face  of  the  anterior 
genital  complex  (PI.  XIV,  figs.  73,  74,  spth.).  It  is  of  a  light 
amber  color,  is  slightly  flattened  dor  so- vent  rally,  measuring  0.435 
mm.  in  its  antero-posterior  diameter  by  0.315  mm.  dorso-ventrally, 
with  an  extreme  length  of  0.46  mm.  It  is  lined  by  a  high  colum- 
nar epithelium,  apparently  ciliated,  but  the  preservation  of  the 
specimen  renders  this  point  uncertain.  A  connective  tissue  cap- 


DISCODORIS    VONIHERINGI    MAC  FARLAND  79 

sule  of  considerable  thickness,  intermingled  with  smooth  muscle 
fibres,  surrounds  the  organ.    The  vaginal  and  uterine  ducts  are 
united  in  a  common  entrance  into  the  spermatotheca.    In  fig.  71 
of  PI.  XIII  is  shown  a  reconstruction  from  sections  with  the 
relations  of  these  ducts  and  of  the  adjacent  organs.    The  vaginal 
duct,  vag.  d.,  is  shown  in  its  proximal  portion  only,  uniting  with 
the  uterine  duct,  u.  d.,  at  their  common  entrance  into  the  sper- 
matotheca, spth.    The  uterine  duct  describes  two  S  shaped  loops 
close  together,  receives  the  slender  duct  of  the  spermatocyst  s*c 
and  opens  into  the  nidamental  gland  at  its  anterior  end,  and'some 
distance  from  the  anterior  margin  of  the  albumen  gland     The 
spermatocyst  is  of  an  elongate  pear  shape,  doubled  upon  itself 
its  greatest  diameter  being  0.19  mm.,  and  its  length  0.330  mm' 

/r, ,eUmmediately  in  fr°nt  °f  and  external  to  the  spermatotheca 
(PI.  XIV,  figs.  73  and  74,  spc.). 

Nidamental-albumen  gland  complex.     The  nidamental-albu- 
men  gland  is  rather  small  in  proportion  to  the  remainder  of  the 
anterior  genital  complex.    It  is  ovoid  in  outline,  the  broader  end 
being  directed  forward  and  outward.    The  upper  surface  is  nearly 
plane,  the  under  surface  slightly  convex.    The  surface  is  marked 
as  usual  by  parallel  convolutions,  which  are  however   not  very 
conspicuous,    being    quite    faint    on    the    central    dorsal    region 
occupied  by  the  albumen  gland.     The  duct  of  the  nidamental 
gland  appears  upon  the  ventro-anterior  surface  (PL  XIV,  fig.  73 
n.d.},  is  large,  and  slightly  flattened  dorso-ventrally.     In  cross' 
section  (PI.  XIII,  fig.  70)  its  lumen  is  seen  to  be  large,  the  dorsal 
ventral  and  anterior  walls  being  thin,  and  of  nearly  equal  thick- 
ness.    The  posterior  wall  bears  two  strong  parallel  longitudinal 
ndges,  d,  and  v.,  projecting  into  the  lumen  and  forming  a  deep 
groove  between  them.    At  the  distal  end  of  the  duct  these  two 
ndges  coalesce,  the  deep  furrow  becoming  reduced  to  a  shallow 
groove  upon  the  crest  of  a  single  ridge.    As  the  duct  approaches 
ie  gland  proper,  this  groove  widens  out,  the  ventral  ridge  de- 
creases and  disappears,  while  the  dorsal  ridge  merges  into  the 
roof  of  the  lumen  of  the  gland. 

Upon  the  external  surface  there  is  but  little  indication  of 
the  division  into  nidamental  and  albumen  glands,  such  as  is 
usually  seen  in  other  Dorididae,  but  in  sections  the  structural 
difference  is  clearly  apparent.  In  PI.  XIII,  fig.  71  the  boundary 


gO  OPISTHOBRANCHIATA  OF  BRAZIL 

of  the  gland  is  approximately  marked  by  the  dotted  oval  line. 
It  occupies  the  median  posterior  portion  of  the  complex.  The 
distal  end  of  the  hermaphroditic  ampulla,  h.  a.,  enters  the  con- 
nective tissue  stroma  of  the  gland  at  its  posterior  end,  giving  off 
the  slender  spermatic  duct,  sp.  d.,  almost  at  right  angles,  and 
then  dilates  into  a  broad  cavity,  2.5  mm.  in  length  and  o.i  mm.  in 
diameter.  Its  wall  is  practically  identical  in  structure  with  that 
of  the  hermaphroditic  ampulla,  and,  like  the  latter  organ,  it  is 
packed  full  of  spermatoza.  It  is  probably  to  be  regarded  as  a 
fertilization  chamber,  since  it  is  here  that  the  ova  first  come  in 
contact  with  the  spermatozoa  from  a  different  individual.  Just 
beyond  the  middle  third  of  the  gland  complex  this  cavity  bends 
sharply  at  right  angles,  dilates  somewhat,  thence  passes  again  in  a 
course  parallel  with  the  long  axis  of  the  gland,  narrowing  rapidly 
to  the  exit  of  the  uterine  duct,  u.  d.,  from  the  anterior  end.  Just 
as  the  above  mentioned  dilation  begins  to  narrow,  a  more  slender 
duct,  0.24  mm.  in  diameter,  is  given  off  at  an  acute  angle,  running 
sharply  backward  and  ventrally,  and  opening  into  the  cavity  of 
the  albumen  gland  at  its  anterior  end.  This  cavity  is  irregularly 
pear-shaped  in  form,  the  broad  end  being  turned  forward  and 
outward,  its  tip  extending  nearly  to  the  proximal  end  of  the 
gland  complex.  It  is  lined  by  a  low  cubical  epithelium,  with 
large  spherical  nuclei.  Into  it  open  on  all  sides  at  intervals  the 
secretory  alveoli  of  the  albumen  gland,  which  may  be  either 
single,  or,  as  is  usually  the  case,  branched  into  a  small  number 
of  divisions.  The  cells  of  the  secretory  alveoli  are  columnar,  ca. 
0.006  mm.  in  average  height,  with  large  conspicuous  nuclei,  but 
their  preservation  did  not  permit  making  out  any  further  details 
of  their  structure.  Dorsal  to  the  entrance  of  the  branch  of  the 
hermaphroditic  duct  into  the  cavity  of  the  albumen  gland,  a 
somewhat  broader  duct  passes  forward  into  the  cavity  of  the 
nidamental  gland  proper.  This  large  cavity  occupies  the  ventral 
portion  of  the  nidamental  gland  throughout  its  whole  extent,  and 
receives  the  short  blind  glandular  diverticula  which  form  the 
mucous  secretion.  In  general  the  cavity  is  undivided,  save  for 
a  few  irregular  ramifications  along  its  posterior  and  outer  border 
into  which  secretory  alveoli  open.  The  lumen  of  the  duct  is  lined 
with  small  cubical  cells  with  large  nuclei ;  in  the  posterior  half  of 
the  gland  these  cubical  cells  are  replaced  by  tall  slender  columnar 


DISCODORIS   VONIHERINGI    MAC  FARLAND  8l 

ones  much  similar  to  those  of  the  terminal  alveoli  of  the  gland. 
An  examination  of  fig.  72  of  PI.  XIV  may  aid  in  a  clearer  per- 
ception of  the  relations  of  the  above  described  cavities.  It 
represents  the  principal  ducts  of  the  gland  complex  in  side  view, 
as  reconstructed  from  serial  sections,  the  glandular  alveoli  and 
other  subordinate  ramifications  being  left  out  for  the  sake  of 
clearness.  The  dotted  line  represents  the  contour  of  the  gland 
complex  as  seen  from  the  front  side.  At  the  posterior  end  of 
the  complex  the  large  hermaphroditic  ampulla,  h.  amp.,  enters, 
gives  off  the  slender  spermatic  duct,  sp.  d,,  which  emerges  from 
the  gland  as  seen  in  fig.  74  of  PL  XIV,  the  duct  passing  forward, 
dilating  into  the  fertilization  chamber,  f.  ch.,  which  makes  a  sharp, 
knee  like  turn  upward,  then  narrowing  rapidly,  gives  off  the 
slender  duct,  x,  to  the  albumen  gland,  and  receives  the  uterine 
duct,  u.  d.,  at  the  distal  end  of  the  gland  complex.  The  duct  x, 
corresponding  doubtless  to  the  oviduct  in  other  Dorids,  passes 
backward,  and  to  the  right,  and  opens  into  the  cavity  of  the 
albumen  gland,  /.  alb.,  triangular  in  this  side  view,  and  terminating 
posteriorly  in  a  blind  blunt  prolongation.  At  its  antero-dorsal 
end  this  cavity  passes  into  the  duct  connecting  it  with  the  cavity 
of  the  nidamental  gland,  alb.  d.,  and  opening  into  the  extreme 
anterior  end  of  the  latter  at  the  exit  of  the  nidamental  duct. 
The  ventrally  placed  large  cavity,  /.  nid.,  into  which  the  alveoli 
of  the  nidamental  gland  pour  their  mucous  secretion,  extends 
backward  to  the  posterior  end  of  the  gland  complex.  Its  dorsal 
surface  is  concave,  the  ventral  convex  in  the  anterior  half  of  the 
organ,  posteriorly  becoming  flatter,  and  finally  the  concavity  is 
shifted  to  the  ventral  side,  the  dorsal  face  being  arched.  From 
the  anterior  end  of  the  cavity  the  broad  nidamental  duct,  n.  d., 
arises  and  emerges  from  the  gland  complex.  In  the  figure  the 
space  between  these  ducts  and  cavities  and  the  bounding  dotted 
line  is  to  be  thought  of  as  filled  with  the  closely  packed  glandular 
diverticula  arising  from  the  cavities  of  the  nidamental  and  albu- 
men glands  respectively. 

The  architecture  of  these  two  glands  appears  to  be  simpler 
in  this  species  than  in  most  other  Dorididae.  From  fig.  72  of  PL 
XIV  the  path  taken  by  the  eggs  in  traversing  the  different  ducts 
from  the  hermaphroditic  ampulla  to  the  nidamental  duct, 
can  be  readily  followed.  No  trace  of  a  second  duct  from  the 


82  OPISTHOBRANCHIATA   OF   BRAZIL 

albumen  gland  to  the  duct  of  the  nidamental  gland,  such  as  that 
described  by  Pohl  ( '95 )  for  Polycera  could  be  found. 

The  circulatory,  respiratory,  excretory  and  nervous  systems 
of  this  species  presented  no  marked  differences  from  other  Disco- 
doridinae. 

The  above  species,  which  is  clearly  different  from  any  hitherto 
described,  I  dedicate  to  Professor  Hermann  Von  Ihering,  the  able 
Director  of  the  Museu  Paulista,  Sao  Paulo,  Brazil,  and  the 
pioneer  in  the  study  of  the  Opisthobranchiata  of  that  country. 

Type  No.  147,  Invertebrate  Series,  Leland  Stanford  Junior 
University  Zoological  Museum. 


Subfamily  DIAULULINAE. 

Body  neither  hard  nor  soft;  depressed  or  subdepressed ; 
notaeum  usually  minutely  villous,  often  silky ;  tentacles  digitiform ; 
branchial  aperture  rounded,  crenulate,  branchial  leaves  tripinnate ; 
anterior  margin  of  foot  bilabiate,  the  upper  lip  notched.  Labial 
armature  none.  Rhachis  of  radula  naked.  Pleurae  multidentate, 
usually  hooked.  Penis  usually  unarmed. 

Genus  PELTODORIS,  Bergh,  1879. 

Peltodoris,  Bergh.  "Ueber  die  Gattung  Peltodoris,"  Mittheil- 
ungen  aus  der  Zoologischen  Station  zu  Neapel,  II,  2, 
1879,  p.  222.  — Malacol.  Untersuchungen,  Sup.  Heft 
I,  1880,  p.  41.  — Neue  Nacktschnecken  der  Siidsee, 
IV,  Jour.  Mus.  Godeffroy,  XIV,  1878.  —Malacol. 
Unters,  XVI,  II,  1889,  p.  815. 

Body  subdepressed,  the  circumference  oval,  subrigid,  minutely 
granular  above.  Tentacles  digitiform.  Branchial  aperture 
rounded,  the  branchiae  of  few  leaves,  usually  tripinnate. 

Labial  armature  none.  Rhachis  of  radula  naked,  pleurae 
multidentate,  the  teeth  hooked. 

Prostate  gland  large.     Penis  and  vagina  unarmed. 
The  genus  Peltodoris  was  established  by  Bergh  in  1879  for 
the  reception  of  the  type  species  P.  atromaculata  Bergh,  from  the 
Mediterranean,  and  for  a  second  species,  P.  crucis  (Oersted), 
from  the  Antilles.     The  genus  is  much  similar  to  Discodoris, 
differing  in  the  less  soft  body,  and  especially  in  the  unarmed 
labial  disc.     Whether  such  a  slight  difference  is   sufficient  to 
establish  a  distinct  genus  or  not  may  be  a  matter  of  doubt. 
In  this  genus  are  placed  the  following  species : 

1.  Peltodoris  atromaculata  Bergh. 

Bay  of  Naples.     Bergh  1.  c. 

2.  Peltodoris  crucis  (Oersted). 

Antilles,  St.  Thomas,  (Riise).     Sainte  Croix,  (Oersted). 
Journ.  de  Conchyliologie,  III,  3,  1863. 

3.  Peltodoris  mauritiana  Bergh. 

Mauritius  Isl.  Bergh,  Mai.  Unters.  XVI,  2,  p.  815. 

4.  Peltodoris  angulata  Eliot. 

East  Africa.    Eliot,  Proc.  Zool.  Soc.    London,  1903. 
Peltodoris  aurea  Eliot. 

East  Africa.    Eliot  1.  c. 


84  OPISTHOBRANCHIATA  OF  BRAZIL 

6.    Peltodoris  rubescens  Bergh. 

Malay  Archipelago.    Bergh,  Siboga  Exp.  1905. 

To  this  list  is  to  be  added  the  following  new  species,  taken 
by  Mr.  Greeley  at  Riacho  Doce,  Alagoas,  July  28,  1899. 
Peltodoris  greeleyi  Sp.  Nov. 
Plate  XV,  figs.  77-82. 

But  one  specimen  is  in  the  collection,  no  notes  save  that  of 
locality  and  date  accompanying  it.  The  animal  was  rolled  up  in 
a  loose  coil,  and  was  apparently  not  much  shrunken  by  the  pre- 
serving fluid. 

EXTERNAL  CHARACTERS. 

Color  and  form.  The  color  of  the  alcoholic  specimen  is  very 
pale  yellowish  pink  everywhere,  there  being  no  special  markings. 
The  dorsum  is  villous,  quite  velvety  to  the  touch  and  quite 
similar  to  Diaulula  in  this  respect.  It  is  equally  rounded  in  front 
and  behind,  the  general  body  shape  being  oblong  elliptical,  with  the 
wide,  rather  fleshy  mantle  edges  projecting  well  beyond  the  foot. 

Branchiae  and  rhinophores.  The  thirteen  branchial  plumes 
are  short,  simply  pinnate  and  arranged  in  a  complete  circle  about 
the  anus,  which  occupies  the  summit  of  a  low  papilla,  the  minute 
pore-like  renal  opening  being  situated  as  usual,  a  little  to  the 
front  and  right.  The  branchiae  were  completely  retracted  within 
the  branchial  pocket,  the  thin  margin  of  which  is  prominent, 
minutely  villous,  and  slightly  inrolled.  The  antero-posterior 
diameter  of  the  opening  is  2.8  mm.,  the  transverse  slightly  less. 
The  margins  of  the  sheath  of  the  deeply  retracted  rhinophores 
are  similarly  villous.  The  clavus  of  the  rhinophores  is  club 
shaped  and  perfoliate,  with  sixteen  leaves  on  either  side.  The 
tentacles  are  short,  conical  and  dorso-ventrally  flattened. 

Foot.  The  foot  is  broad  and  muscular,  contracted,  the 
anterior  end  rounded  and  bilabiate,  the  upper  slightly  notched. 

Dimensions.  The  approximate  length  of  the  partly  rolled 
up  specimen  is  18.0  mm.,  with  a  maximum  width  of  10.0  mm. 

INTERNAL  ANATOMY. 

Integument.  The  dorsal  integument  is  thin,  strengthened 
everywhere  with  minute  spicules.  Around  the  base  of  each 
papilla  of  the  velvety  surface  of  the  dorsum  is  arranged  a  radial 


PELTODORIS    GREELEYI    MAC  FARLAND  85 

series  of  short,  rod  like  spicules  which  are  continued  up  into 
the  papilla  to  its  summit.  The  minute  papilla,  which  lend  to  the 
surface  of  the  dorsum  its  velvety  appearance,  are  supported  by 
a  large  number  of  spicules,  distinguishable  into  two  classes.  In 
the  axial  portion  of  each  papilla  are  found  four  to  eight  stout, 
blunt,  cylindrical  spicules  at  right  angles  to  the  general  body 
surface.  Placed  obliquely  around  these  in  a  radiate  manner, 
their  central  tips  forming  a  close  ring  at  the  summit  of  the 
papilla,  are  a  variable  number  of  more  slender,  pointed  spicules 
of  the  type  generally  found  throughout  the  thickness  of  the 
integument  (PI.  XV,  fig.  77).  The  average  length  of  the  central 
spicules  is  0.07  mm.,  their  diameter  0.006  mm.,  while  the  oblique 
spicules  average  o.n  mm.  in  length  and  0.004  mm-  m  diameter. 
The  pseudo-peritoneum  is  colorless  throughout,  all  the  viscera 
being  covered  with  a  delicate  sheet  of  connective  tissue.  Loosely 
attached  to  the  dorsal  surface  of  the  central  nervous  system  is  the 
bilobed  blood  gland,  very  thin  and  flat,  its  anterior  lobe  being 
much  smaller  than  the  posterior  one. 

ALIMENTARY  SYSTEM. 

The  oral  tube  is  short,  broad  and  muscular,  1.25  mm.  long 
by  1.75  mm.  wide,  partly  everted  through  the  mouth  opening. 
No  trace  of  a  specialized  labial  armature  was  present  other  than 
the  simple  cuticular  thickening. 

Radula.  The  pharyngeal  bulb  is  a  nearly  spherical  mass, 
2.1  mm.  in  diameter,  the  radula  sheath  forming  but  a  slight 
prominence  upon  the  lower,  posterior  surface.  The  radula  is 
broad,  short  and  deeply  grooved.  The  teeth  are  in  49  rows,  of 
which  the  first,  the  oldest,  are  more  or  less  worn  away  and 
incomplete.  The  rhachis  is  naked,  the  pleurae,  60  in  number 
on  each  side,  are  strongly  hooked,  and  of  a  similar  shape  through- 
out. The  bases  are  moderately  thick  and  heavy,  the  hooks 
blunt  and  flattened  (PI.  XV,  figs.  78,  81).  The  shaft  and  hook 
of  each  tooth  lie  in  the  same  plane,  the  tip  of  the  hook  not  being 
directed  toward  one  side  as  is  usually  the  case.  The  dimensions 
of  a  typical  tooth  are:  length  of  base  0.082  mm.,  height  of 
hook  0.049  mmv  width  of  base  0.005  mm-  The  outermost 
tooth  of  each  row  is  smaller  than  the  remaining  ones  (PI.  XV,  fig. 
79),  as  are  also  the  innermost  pleurae  (PI.  XV,  fig.  80).  The 


86  OPISTHOBRANCHIATA  OF  BRAZIL 

dental    formula    for   the  whole    radula    may   be    expressed    as 
60  :o  :6ox49. 

Visceral  complex.  The  salivary  glands  are  short  and  broad, 
2.5  mm.  in  length,  scarcely  extending  beyond  the  circumesopha- 
geal  ring  of  the  central  nervous  system.  The  esophagus  is  short 
and  wide,  passing  downward  and  backward  into  the  large  stomach, 
which  lies  in  the  usual  V  shaped  groove  in  the  upper  anterior 
border  of  the  liver.  The  stomach  is  broadly  wedge  shaped  above, 
4.5  mm.  in  length,  3.0  mm.  wide  and  2.25  mm.  in  depth,  pre- 
senting a  somewhat  triangular  cross  section.  The  esophagus 
enters  at  its  lower  anterior  border,  the  intestine  arising  from  the 
upper  posterior  end  and  passing  backward  to  the  anus,  lying  in  a 
groove  in  the  upper  surface  of  the  liver  throughout  its  course. 
The  latter  organ  presents  the  form  of  a  blunt  cone,  the  anterior 
end  deeply  notched  for  the  reception  of  the  stomach,  and  facetted 
by  the  pressure  of  the  anterior  genital  complex.  The  cavity  of 
the  liver  opens  widely  into  that  of  the  stomach  on  the  ventral 
median  line,  immediately  behind  the  opening  of  the  esophagus. 
No  bile  cyst  is  present. 

REPRODUCTIVE  SYSTEM. 

Hermaphroditic  gland  and  duct.  The  surface  of  the  liver 
is  covered  everywhere  save  on  the  central  portion  of  the  gastric 
groove,  the  anterior  face  and  the  antero-ventral  surface  by  the 
ramifications  of  the  hermaphroditic  gland.  Its  duct  arises  by 
the  union  of  a  number  of  delicate  tubules  from  the  lobules  of 
the  mid-dorsal  face,  immediately  behind  the  stomach.  It  courses 
forward  and  downward,  between  the  right  surface  of  the  stomach 
and  the  anterior  lobe  of  the  liver,  for  a  distance  of  3.5  mm.  and 
dilates  into  the  white  hermaphroditic  ampulla  on  the  lower 
surface  of  the  anterior  genital  mass  (PI.  XV,  fig.  82,  h.  a.}. 

Anterior  genital  complex.  The  organs  of  this  complex  are 
very  compact,  convex  upon  the  outer  and  inner  surfaces,  in 
lateral  view  oval,  from  above  more  pointed  posteriorly  than  in 
front.  The  extreme  length  of  the  complex  is  4.6  mm.,  its  width 
2.5  mm.,  and  height  3.5  mm.  Its  inner  face  bears  a  shallow 
broad  groove,  deepening  toward  the  upper  margin.  Anterior 
to  this  groove  and  forming  a  large  part  of  its  anterior  wall  is 
a  smooth,  light  brown  surface,  the  wall  of  the  spermatotheca  (PI. 


PELTODORIS  GREELEYI  MAC  FARLAND  87 

XV,  fig.  82,  spth.).  Below,  wedged  in  between  the  spermatotheca 
in  front  and  the  albumen  gland  behind,  appears  the  surface  of 
the  glistening  white  hermaphroditic  ampulla.  Encircling  the 
spermatotheca  and  this  ampulla  is  a  lobulated  mass,  the  prostate 
gland  (PI.  XV,  fig.  82,  pr.}.  Posterior  to  the  hermaphroditic 
ampulla  and  the  spermatotheca,  the  inner  face  of  the  anterior 
genital  mass  is  made  up  principally  of  the  albumen  gland,  finely 
convoluted  and  of  a  light  yellow  color,  surrounded  above,  behind 
and  below  by  the  thicker  convolutions  of  the  pinkish  nidamental 
gland.  The  lower  posterior  border  of  the  complex  is  occupied  by 
a  broad  convolution  of  the  nidamental  gland,  which  is  of  a 
reddish  hue,  markedly  distinct  from  the  remainder  of  the  mass. 
In  the  figure  82  of  Plate  XV,  the  nidamental  and  albumen  glands 
have  been  dissected  away,  and  are  not  shown. 

Hermaphroditic  ampulla.  The  hermaphroditic  duct  dilates 
into  its  glistening  white  ampulla,  midway  of  the  inner  face  of 
the  anterior  genital  complex.  This  ampulla  is  somewhat  lunate 
in  form,  curving  downward  in  a  groove  between  the  spermato- 
theca and  the  albumen  gland,  thence  outward  and  upward  upon 
the  external  face  of  the  complex  to  a  point  immediately  below 
and  in  front  of  the  spermatocyst,  where  it  narrows  suddenly, 
gives  off  the  spermatic  duct  (PI.  XV,  fig.  82,  sp.  d.},  and  passes 
inward  and  upward  into  the  nidamental  gland. 

Prostate  gland  and  penis.  The  very  short  spermatic  duct 
passes  at  once  into  the  large  lobulate  prostate  gland  (PI.  XV, 
fig.  82,  pr.),  overlying  and  forming  the  whole  of  the  front  sur- 
face of  the  complex.  From  its  superior  surface  is  given  off  the 
relatively  long  vas  defenens  (PI.  XV,  fig.  82,  v.  def.),  which 
describes  an  irregular  loop,  free  from  the  surface  of  the  anterior 
genital  mass,  above  its  antero-median  transverse  groove,  and 
passes  downward  and  outward  into  the  praeputium.  The  prae- 
putium  is  1.5  mm.  long  by  i.o  mm.  in  maximum  width,  tapering 
inward  to  the  vas  deferens.  Within  it  is  inclosed  the  retracted 
glans  penis,  cylindro-conical  in  form,  its  length  0.78  mm.,  its 
greatest  diameter  0.16  mm.,  tapering  gradually  to  a  truncate 
tip  with  a  terminal  diameter  of  0.009  mm->  smooth  and  entirely 
unarmed. 


88  OPISTHOBRANCHIATA  OF  BRAZIL 

Vagina  and  duct.  Parallel  to  the  praeputium  and  a  little 
behind  it  pass  the  more  slender  vagina  and  vaginal  duct.  Their 
combined  length  is  much  less  than  that  of  the  vas  deferens  and 
the  praeputium.  The  vaginal  duct  (PL  XV,  fig.  82,  vag.  d.), 
passes  inward  between  the  prostate  gland  in  front,  and  the  sper- 
matotheca,  opening  into  the  latter  after  a  course  of  ca.  2.0  mm. 
The  spermatotheca  (PL  XV,  fig.  82,  spth.)  is  ellipsoidal  in  form, 
3.0  mm.  in  length  by  2.5  mm.  in  width,  and  is  covered  almost  en- 
tirely by  the  prostate  gland  and  the  adjacent  organs,  being  exposed 
only  for  a  small  portion  of  its  extent  upon  the  inner  face  of  the 
anterior  genital  complex.  The  uterine  duct  (PL  XV,  fig.  82,  u. 
d.)  is  given  off  very  close  to  the  entrance  of  the  vaginal  duct, 
passes  directly  outward,  becoming  visible  upon  the  outer  surface 
of  the  mass,  curves  backward  beneath  the  spermatocyst,  and 
opens  into  the  cavity  of  the  nidamental  gland.  It  receives,  not 
far  from  its  origin,  the  short  duct  of  the  pear  shaped  spermato- 
cyst, which  lies  upon  the  upper  outer  border  of  the  median 
portion  of  the  complex.  In  length  it  measures  i.o  mm.,  in 
width  0.5  mm. 

Owing  to  the  loss  of  this  portion  of  the  material,  which 
was  being  dissected  at  the  time  of  the  earthquake  of  April  18, 
1906,  I  am  unable  to  give  any  further  details  as  to  the  structure 
of  the  prostate,  nidamental  and  albumen  glands. 

The  anatomy  of  the  other  organs  of  this  species  do  not  depart 
markedly  from  the  other  members  of  the  genus. 

This  species  is  named  in  memory  of  Dr.  Arthur  W.  Greeley, 
the  zoologist  of  the  expedition,  whose  untimely  death  cut  short 
a  life  full  of  promise  in  his  profession. 

Type  No.  148,  Invertebrate  Series,  Leland  Stanford  Junior 
University  Zoological  Museum. 


TRIBE  II.    AEOLIDOIDEA. 

Genital  duct  diaulic,  the  male  and  female  openings  con- 
tiguous. Liver  ramified,  extending  into  the  latero-dorsal  integu- 
mentary papillae.  Pharyngeal  bulb  bearing  a  pair  of  lateral 
mandibles. 

Family  AEOLIDIADAE. 

Body  slug-like,  dorso-lateral  papillae  spindle,  or  club  shaped 
each  terminating  in  a  cnidosac  armed  with  nematocysts  Head 
bearing  a  pair  of  simple  tentacles,  and  a  pair  of  simple  or  perfoliate 
rhmophores,  non-retractile  into  sheaths.  Foot  elongate,  the  ante- 
rior angles  frequently  prolonged  into  tentacles. 

Subfamily  AEOLIDIANAE. 

Body  somewhat  depressed  or  subdepressed.  Dorsal  papillae 
more  or  less  compressed. 

Masticatory  margin  of  mandibles  smooth  or  nearly  so 
Radula  uniserial,  the  teeth  wide,  pectinate. 

Penis  unarmed. 

Genus  SPURILLA,  Bergh,  1864. 

Spurilla,  Bergh.     Anatomiske  Bidrag  til  Kundskab  om  Aeoli- 
dierne.     K.  Dansk.  Vidensk.  Selsk.  Skr.,  5te  Raekke, 
Naturvid.  og  Math.  Afh.,  VII,  1864,  p.  205,  Tab.  VB 
—Bergh,  Beitraege  zur  Kenntniss  der  Mollusken  des 
bargassomeeres.     Verh.  d.  k.  k.  zool.-bot.  Gesellschaft 
m  Wien,  XXI,  1871,  p.  1283.    —Bergh,  Beitraege  zur 
Kenntniss  der  Aeolidiaden,  IV,  Verh.  d.  k.  k.  zool  -bot 
Ges    m  Wien,  XXVI,  1877,  p.  758-761.     — Trinchese, 
b.   Anatomia   e   Fisiologia   della   Spurilla  neapolitana. 
Memorie   dell'Accademia   delle   Scienze   dell'Istituto   di 
Bologna,  T.  IX,  Ser.  Ill,  1878,  p.  405-430.    —Bergh 
Beitraege    etc.,    VII,    1.    c.    XXXII,    1882,    p     12-10' 
—Bergh,  Beitraege  etc.,  VIII,  1.  c.  XXXV,  1885,  p.  26- 
27-     — Vayssiere,  A.  Recherches  zool.  et  anat.  sur  les 
Mollusques  Opistobranches  du  Golfe  de  Marseille,  II. 
Annales  du  Musee  d'Histoire  Naturelle  de  Marseille 
Zoologie,  III,  1888,  p.  in.    —Supplement,  Ibid,  VIII 
1903,  P-  86. 


90  OPISTHOBRANCHIATA   OF   BRAZIL 

Body  somewhat  elongate,  not  depressed.  Rhinophores  per- 
foliate.  Anterior  angles  of  foot  not  prominent.  Cerata  cylindro- 
conical,  arranged  in  groups,  each  of  which  is  borne  upon  a 
slight,  crescentic,  dorso-lateral  elevation  of  the  integument. 

Masticatory  margin  of  mandibles  long,  minutely  denticulate, 
or  smooth. 

Radula  uniserial,  the  teeth  pectinate,  emarginate  in  the  center. 

This  genus  was  proposed  by  Bergh  in  1864  for  the  reception 
of  Delle  Chiaje's  Eolis  neapolitana  as  the  type  species.  In  1871 
he  transferred  to  this  genus  a  second  species,  Sp.  sargassicola 
(Kroyer),  and  in  1882  and  1885,  in  the  papers  cited  above,  made 
further  additions  to  the  knowledge  of  the  anatomy  of  the  type 
species,  which  had  been  already  extensively  studied  by  Trinchese 
in  1878.  Vayssiere  added  to  this  in  his  excellent  researches 
upon  the  Opisthobranchs  of  the  Gulf  of  Marseilles,  in  1903 
recognizing  a  third  distinct  species,  Sp.  inornata  (A.  Costa). 
The  Siboga  collections  contained  a  fourth  species,  which  was 
described  by  Bergh  in  1905  in  his  beautiful  work  upon  the 
Opisthobranchiata  of  that  expedition. 

At  the  present  time  the  list  of  species  described  as  belonging 
to  this  genus  is  the  following : 

1.  Spurilla  neapolitana  Delle  Chiaje). 

Mediterranean,  Cape  Verd  Islands. 

2.  Spurilla  sargassicola  (Kroyer). 

Sargasso  Sea,  Atlantic  Ocean. 

3.  Spurilla  inornata  (A.  Costa). 

Mediterranean. 

4.  Spurilla  orientalis  Bergh. 

Kei  Island,  Malay  Archipelago. 

All  three  of  these  species  are  closely  related,  the  first  two 
being  held  by  Bergh  to  be  questionably  distinct.  The  following 
description  deals  with  the  first  member  of  this  genus  thus  far 
taken  from  the  West  Atlantic.  After  a  careful  comparison  of  its 
structure  with  that  of  Sp.  neapolitana,  and  with  the  description 
of  the  others,  I  am  of  the  opinion  that  it  represents  a  distinct 
species,  though  certainty  in  this  regard  can  only  be  secured  by  the 
study  of  a  series  of  specimens. 


SPURILLA    BRAZILIANA    MAC  FARLAND  9! 

Spurilla  braziliana  Sp.  Nov. 
Plates  XVI,  XVII,  XVIII  and  XIX;  Figs.  83-96. 

i  h  .But  °n^Pecimen  was  taken  by  the  expedition,  the  locality 
label  reading  "Riacho  Doce,  Alagoas,  July  2gf  1899."  The  preset 
vation  of  the  specimen  was  rather  poor,  it  having  been  k  led 
m  a  distorted  position,  with  the  head,  tentacles  and  rhinopho  es 
strongly  contracted  and  the  posterior  portion  of  the  body  re- 
curved dorsally.  The  cerata  had  nearly  all  fallen  off,  but  were 
preserved  m  the  bottle.  The  original  color  had  entirely  disap! 
peared,  nor  were  any  notes  taken  as  to  the  color,  dimensions  or 
appearance  m  life.  The  animal  in  the  preserved  condition  had 
a  uniform,  pale  pinkish  coloration. 

EXTERNAL  CHARACTERS. 

Dimensions^  The  total  body  length  is  circa  23.0  mm.,  of 
which  the  length  of  the  foot  makes  up  18.5  mm.,  the  quite  dis- 
torted head  region  the  remainder. 

Body  form.  The  general  body  form  is  slender  and  somewhat 
compressed,  tapering  posteriorly  to  a  short  bluntly  pointed  tail 
the  general  body  form  being  similar  to  that  of  the  other  species 
of  the  genus.  The  mouth  is  everted  and  reflexed,  the  whole 
head  region  being  strongly  contracted.  The  oral  tentacles  in 
their  contracted  state  are  tapering,  with  blunt  extremities,  their 
basal  diameter  being  0.5  mm.,  and  approximate  length  3.0  mm 

Rhinophores.  The  strongly  contracted  rhinophores  are  per- 
toliate,  the  clavus  bearing  eight  prominent  leaves,  which  alternate 
on  the  posterior  side  with  an  equal  number  of  lower  ones  that 
extend  forward,  half  way  around  the  clavus  from  the  posterior 
median  line. 

Cerata.  The  cerata  are  lanceolate,  flattened,  and  variously 
curved,  m  part  due  to  the  action  of  the  preservative  but  also 
often  showing  the  S  shaped  curves  common  in  Spurilla  neapoli- 
tana.  The  smaller  cerata  are  more  rounded  and  conical  in  form 
Ihe  cerata  are  arranged  in  eight  groups  along  the  dorso-lateral 
margins  of  the  body  (PI.  XVII,  figs.  90,  91).  Each  of  the  first  five 
these  groups  is  made  up  of  two  slightly  curved  rows  of  cerata, 
the  upper  ends  of  the  rows  approaching  each  other  and  uniting 
to  form  an  arc  like  figure,  borne  upon  a  slight  integumentary 
elevation.  The  anterior  limb  of  each  of  these  arcs  contains  more 


OPISTHOBRANCHIATA   OF   BRAZIL 


cerata  than  the  posterior  one,  the  number  in  both  decreasing  in 
each  group  from  the  first  backward,  until  the  posterior  limb 
entirely  disappears,  the  anterior  row  being  alone  represented  in 
the  groups  from  the  sixth  onward.  In  figs.  90  and  91  the 
bases  of  the  cerata  are  outlined  by  small  circles,  indicating  the 
relative  size  and  positions  of  these  groups.  The  number  does 
not  exactly  correspond  upon  the  two  sides  of  the  body  for  each 
group,  but  the  difference  is  not  marked,  the  total  number  for  the 
right  side  being  eighty,  that  for  the  left  eighty-one.  The  distri- 
bution of  the  cerata  in  the  anterior  and  posterior  limbs  of  the 
groups  is  shown  in  the  following  tabulation. 


Cerata  Group 

RIGHT  SIDE 

LEFT  SIDE 

Anterior 
Limb 

Posterior 
Limb 

Anterior 
Limb 

Posterior 
Limb 

1st  group 

11 

7 

13 

8 

2nd    " 

10 

7 

10 

6 

3rd     " 

8 

5 

8 

7 

4th     " 

7 

4 

9 

5 

5th     " 

6 

3 

6 

2 

6th     " 

5 

4 

7th     " 

4 

2 

Sth     " 

3 

1 

Totals 

54 

26 

53 

28 

These  figures  may  be  expected  to  vary  somewhat  in  individ- 
uals of  different  sizes,  as  they  do  also  for  the  Mediterranean 
species. 

The  anterior  limb  of  the  first  group  begins  in  front  of  and 
below  the  bases  of  the  rhinophores.  The  reproductive  openings 
are  situated  close  together,  below  the  first  arc  of  cerata  on  the 
right  side;  the  anal  opening  is  placed  on  a  prominent  tubular 
papilla,  well  up  on  the  same  side,  and  is  included  in  the  span 
of  the  second  group.  The  opening  is  large,  with  slightly  lobulated 
margins  (PI.  XVI,  fig.  88).  The  very  minute  renal  opening  is 
immediately  in  front  of  its  base. 


SPURILLA    BRAZILIANA     MAC  FARLAND  93 

Foot.  The  foot  is  rather  narrow,  tapering  posteriorly  into 
a  short  bluntly  pointed  tail.  The  anterior  margin  is  thickened, 
with  a  distinct,  median  groove,  its  outer  angles  are  short  and 
pointed  (PL  XVI,  fig.  85).  The  total  length  of  the  foot  is  18.5 
mm.,  the  diameter  of  its  anterior  portion  3.5  mm.,  narrowing 
to  3.0  mm.  about  midway  of  its  length. 

Pharyngeal  bulb.  The  pharyngeal  bulb  is  nearly  oval  in 
outline,  broadest  on  its  upper  posterior  border,  the  sides  sloping 
toward  each  other  below.  In  front  the  dark  brown  hinge  portion 
of  the  mandibles  is  thickened  and  conspicuous.  Its  maximum 
measurements  are,  length  3.0  mm.,  breadth  1.8  mm.,  and  height 
1.8  mm.,  being  fully  one-third  smaller  than  the  pharyngeal  bulb 
of  specimens  of  Sp.  neapolitana  of  the  same  dimensions  of  the 
body. 

Mandibles.  The  mandibles  (PI.  XVII,  figs.  92,  93),  are 
similar  in  general  form  to  those  of  Sp.  neapolitana,  but  decidedly 
smaller.  They  are  elongate  oval  in  outline,  3.0  mm.  in  greatest 
length  by  2.0  mm.  in  greatest  width.  Each  mandible  is  made  up 
of  three  portions,  the  head,  the  body  and  the  masticatory  process. 
The  head  is  massive,  strongly  arched  in  front  and  below,  and 
bears  the  fulcrum,  or  hinge  (PI.  XVII,  figs.  92,  d.,  93,  e.},  a 
strong  dark  yellow  curved  ridge,  its  concavity  directed  downward. 
In  the  left  mandible  the  crest  of  this  ridge  is  single  (PI.  XVIII, 
fig.  95,  c.},  fitting  into  a  groove  between  the  diverging  double 
crests  of  the  corresponding  ridge  of  its  fellow  of  the  opposite  side 
(PI.  XVIII,  fig.  94,  c.). 

The  body  is  elliptical,  thin,  and  strongly  arched  in  front, 
less  so  behind,  its  whole  extent  strongly  marked  by  the 
lines  of  growth,  parallel  to  the  posterior  border.  Its  inner 
face  is  concave,  the  outer  convex.  The  masticatory  process  is 
made  up  of  a  triangular  lamina,  widest  behind,  attached  to  the 
ventral  margin  of  the  body  of  the  mandible.  Its  posterior  end 
is  free  from  the  mandible  and  is  separated  from  it  by  a  deep 
sinus  (PI.  XVII,  figs.  92,  93,  c.}.  The  ventral  margin  (PI.  XVII, 
figs.  92,  93,  b.)  is  much  thickened  and  broader,  and  is  prolonged 
forward,  curving  upward  and  backward  to  the  posterior  end  of 
the  fulcrum  (PI.  XVIII,  figs.  94,  95,  d.).  It  serves  as  the  masti- 
catory margin  of  the  mandible,  and  shows  no  trace  of  the 
denticles  characteristic  of  the  other  species  of  Spurilla. 


<j4  OPISTHOBRANCHIATA  OF   BRAZIL 

According  to  the  descriptions  and  figures  of  Trinchese  ('78) 
the  single  crest  is  found  upon  the  fulcrum  of  the  right  mandible, 
the  double  crest  upon  the  left  one  in  Spurilla  neapolitana,  which 
is  the  reverse  of  the  condition  here  described.  In  the  preparations 
which  I  have  made  of  the  mandibles  of  Sp.  neapolitana  the  rela- 
tions of  the  single  and  double  crests  is  the  same  as  that  which  I 
have  found  in  Sp.  braziliana.  I  am  at  a  loss  to  explain  the  con- 
tradiction in  results. 

Radula.  The  radula  is  uniserial,  consisting  of  a  series  of 
eighteen  strongly  arched  slightly  emarginate  pectinate  plates 
of  an  amber  color.  These  plates  increase  rapidly  and  regularly 
in  size  from  before  backward,  and  present  a  slightly  convex  ante- 
rior face.  The  first  five  plates  have  their  central  denticles  worn 
and  broken,  the  last  five  are  still  inclosed  in  the  radula  sheath 
where  they  are  developed.  The  dimensions  of  the  individual 
teeth  range  from  a  basal  width  of  0.27  mm.,  and  a  height,  meas- 
ured from  the  middle  of  the  base  line  to  the  top  of  the  middle 
denticle,  of  0.225  mm.,  in  the  first  plate,  to  a  width  of  0.425  mm., 
and  a  height  of  0.30  mm.  in  the  eighteenth  plate.  The  relative 
proportions  are  well  shown  in  PI.  XVI,  figs.  83  and  84,  which 
illustrate  the  twelfth  and  the  first  plates  of  the  radula  respectively. 

Each  plate  is  slightly  emarginate  at  its  summit  (PI.  XVI,  fig. 
89),  but  none  so  much  so  as  to  give  the  bilobed  appearance 
figured  by  Bergh  ('64,  '71),  Trinchese  ('78)  and  Vayssiere  ('88, 
'03)  for  the  other  species  of  this  genus.  The  denticles  are  slender 
and  lanceolate,  the  lateral  ones  slightly  curved,  the  remainder 
straight,  increasing  in  length  from  the  sides  upward,  and  reaching 
a  maximum  height  about  the  eighth  or  tenth  from  the  center.  The 
central  denticle  is  low  and  broad,  usually  with  a  small  denticle 
next  to  it  on  either  side,  the  succeeding  ones  increasing 
in  length  rapidly.  The  number  of  denticles  in  the  first  plate  is 
49:i:49;  in  the  fifth  39:1:40;  in  the  twelfth  57:1:53;  in  the 
fifteenth  61  :i  163;  and  in  the  eighteenth  49:1 147,  the  increase  in 
number  thus  being  irregular.  In  a  radula  taken  from  an  indi- 
vidual of  Sp.  neapolitana  of  the  same  body  dimensions  this  in- 
crease in  the  number  of  denticles  is  much  more  regular,  repre- 
sentative plates  running  as  follows.  First  plate  18:1:15;  fifth 
plate  23  :i :  23 ;  tenth  plate  34  :i :  34 ;  twelfth  plate  32  :i :  35 ;  fifteenth 
plate  35  :i :  37 ;  eighteenth  plate  52  :i :  44 ;  and  in  the  twenty-sixth 


SPURILLA    BRAZILIANA    MAC  FARLAND  95 


twenty-sixt,    In  S, 


as  exhibited 


capsule,  from  which  in  the  specimen  at  hand  the  gang  iahad 
m  part  shrunken  away,  the  general  preservation  predudtg  "nv 
sahsfactory  detailed  study  of  the  cells  and  fibre  tracts  in-  sertionT 
though  the  general  relations  could  be  readily  made  out      For 
companson  several  specimens  of  Sp.  neafoliLa  were  a  so  *s 
sected.    In  general  there  is  no  great  difference  between  the  two 
spec.es   but  some  marked  discrepancies  were  noted  between  tie 
Neapohtan  species  and  the  figures  given  for  it  by  BergT  "77) 
and  by  Tnnchese  ('78),  especially  in  y       «"»J 

the  nerves     In  Bergh's  fig.  4,  PI.  XII,  the  nerves  appeaf  to  be 
'  di 


u._     j  .  — -»y    i_>v,ing  nciiuer  num- 

r  mentioned  in  the  text,  the  author  manifestly  laying- 

most  stress  upon  the  form  and  grouping  of  the  ganglia     In    he 

dd    CerT  °d  ^T  "NUOV°  RiCerChC  SUl1'  O^n-azion 
Cervello    degh    Eolididei,"    Memorie    dell'Accademia    delle 
Scienze  dell  Institute  di  Bologna,  1875,  Serie  III,  T.  V,  he  devotes 
his  attention  to  certain  peculiarities  of  the  nerve  cells  as  seen  in 
preparations,  cleared  in  glycerine  and  flattened  under  a  cover 
glass,  his  figure  of  Tavola  I  giving  but  a  faint  idea  of  the  actual 
form  of  the  ganglia  and  the  origins  of  their  nerves.     In  his 
Anatomia  e  Fisiologia  della  Spurilla  neapolitana,"  cited  above 
this  is  corrected  in  the  figures  of  Tavola  XI,  which  present  the 
5t  representations  of  the  central  nervous  system  of  this  Eolid 
yet  published.    In  the  figure  of  the  same  for  Sp.  braziliana,  given 
on  PI    XIX,  fig.  96,  I  have  adopted  the  designations  used  by 
Tnnchese  for  the  nerves  for  the  sake  of  ease  of  comparison 
ough  I  must  disagree  with  him  as  to  the  actual  origin  and 


go"  OPISTHOBRANCHIATA   OF   BRAZIL 

relations  of  some  of  these  nerves  in  both  the  Brazilian  and  the 
Neapolitan  forms. 

In  studying  both  species  the  central  nervous  system  was 
carefully  freed  from  its  attachments,  stained  in  Paracarmine,  and 
cleared  in  glycerine.  To  facilitate  microscopic  examination,  and  to 
avoid  unnecessary  displacement  of  the  parts  concerned,  a  piece 
of  glass  rod  was  drawn  out  in  a  flame  to  the  approximate  diameter 
of  the  esophagus  of  the  animal.  A  short  bit  of  this  was  passed 
through  the  circumesophageal  loop  of  the  central  nervous  system, 
and  the  whole  mounted  on  a  slide  having  a  suitable  depression 
ground  in  it.  The  preparation  may  then  be  rotated  and  examined 
from  all  sides,  without  danger  of  disturbing  the  relations  of  its 
parts.  The  use  of  the  Zeiss  binocular  dissecting  microscope 
enormously  facilitates  the  recognition  of  the  relations  of  the 
ganglia  and  their  nerves. 

The  dorsal  portion  of  the  nerve  collar  is  made  up  of  the 
fused  cerebro-pleural  ganglia  (PL  XIX,  fig.  96,  c.  pi.  £.),  in  con- 
tact along  the  median  line,  the  cerebral  portions  being  joined  by 
the  very  short  and  broad  cerebral  commissure.  The  two  ganglia 
are  marked  off  from  each  other  by  a  slight  transverse  constriction, 
dividing  the  complex  into  two  approximately  equal  portions, 
the  anterior,  cerebral  one  being  slightly  larger  than  the  posterior, 
pleural  part.  While  in  the  main  the  nerve  cells  correspond  in 
their  distribution  to  these  divisions,  there  is  no  middle  region 
between  the  two  entirely  free  from  them.  The  length  of  the 
whole  complex  is  0.6  mm.,  the  transverse  diameter  of  each  cere- 
bral portion  0.345  mm.,  that  of  the  pleural  portion  0.315  mm. 

Lateral  to  the  esophagus  are  situated  the  ellipsoidal  pedal 
ganglia  (PL  XIX,  fig.  96,  ped.  g.},  connected  to  the  cerebro-pleural 
complex  by  the  very  short  cerebro-pedal  and  pleuro-pedal  con- 
nectives. The  maximum  length  of  the  pedal  ganglia  is  0.33  mm., 
with  an  antero-posterior  diameter  of  0.21  mm.,  and  a  dorso- 
ventral  diameter  of  0.225  mm- 

The  ventral  portion  of  the  circumesophageal  ring  is  made 
up  of  the  commissures.  These  are  three  in  number,  two  of  which 
are  united  together  in  a  common  sheath,  forming  a  broad  band. 
In  this  band  are  included  the  broad  pedal  and  the  narrower  sub- 
cerebral  commissures  (PL  XIX,  fig.  96,  ped.  com.).  Separate 
from  this,  but  close  to  it  is  the  slightly  longer  pleural  commissure 


SPURILLA    BRAZILIANA    MAC  FARLAND  97 

(PL  XIX,  fig.  96,  pi.  com.),  taking  its  origin  from  the  pleural 
portion  of  the  cerebro-pleural  complex.  At  a  point  about  one- 
fourth  of  its  length  from  the  left  side  it  gives  off  a  moderately 
strong,  unpaired  nerve,  the  N.  genitalis  (PI.  XIX,  fig.  96,  n.  g.). 
This  is  described  and  figured  by  Bergh  as  arising  from  the  right 
side  in  Sp.  neapolitana.  In  the  Brazil  species  no  ganglion  cells 
were  found  at  the  origin  of  the  nerve.  To  these  three  commis- 
sures should  be  added  a  fourth  loop  around  the  esophagus,  which 
is  separated  from  them  by  some  distance.  This  is  formed  by  the 
cerebro-buccal  connectives  and  the  buccal  ganglia.  These  slender 
connectives  (PI.  XIX,  fig.  96,  cer.  buc.  con.)  arise  from  the  cere- 
bral ganglia  just  below  and  in  front  of  the  eyes.  The  buccal 
ganglia  themselves  are  quite  similar  to  those  of  the  Neapolitan 
species.  They  are  oval  in  form,  0.24  mm.  long  by  0.21  mm.  broad, 
and  are  united  by  a  very  short  (0.042  mm.)  and  broad  com- 
missure. A  pair  of  small  gastro-esophageal  ganglia  are  closely 
united  to  them. 

From  the  antero-dorsal  portion  of  the  cerebral  ganglia  arise 
the  short  stout  olfactory  nerves  (PI.  XIX,  fig.  96,  off.  n.),  which 
dilate  into  the  very  large  elliptical  olfactory  ganglia  at  the  base 
of  the  rhinophores.  These  nerves  should,  perhaps,  be  termed 
cerebro-olfactory  connectives,  the  name  olfactory  nerves  being 
reserved  for  the  branches  arising  from  the  summit  of  the  ganglia, 
which  are  distributed  to  the  olfactory  epithelium  of  the  rhino- 
phores. 

The  small  optic  ganglia,  bearing  the  eyes  (PI.  XIX,  fig.  96, 
e.),  lie  upon  the  dorso-lateral  margin  of  the  cerebral  ganglia,  in 
direct  contact  with  them,  and  above  the  origin  of  the  cerebro- 
pedal  connectives.  Immediately  behind  these  are  the  approx- 
imately spherical  otocysts  (PI.  XIX,  fig.  96,  ot.),  0.045  mm-  m 
diameter,  containing  many  small  otoconia  of  an  ellipsoidal  shape. 
In  sections  the  otocysts  are  seen  to  lie  upon  and  behind  a  group 
of  small  ganglion  cells,  outside  the  limits  of  the  cerebro-pleural 
complex,  and  probably  to  be  regarded  as  an  otic  .ganglion,  but 
the  preservation  of  the  material  precluded  any  decision  as  to 
their  exact  relationships. 

Plate  XIX,  fig.  96  shows  the  origin  of  the  nerves  from  the 
central  nervous  system  in  Sp.  brasiliana,  being  much  the  same 
as  that  given  by  Trinchese  for  Sp.  neapolitana.  Nerve  VII 


98  OPISTHOBRANCHIATA   OF   BRAZIL 

is  worthy  of  separate  notice,  however.  I  am  unable  to  confirm 
Trinchese's  figures  as  to  its  origin  in  either  species.  He  shows 
it  as  arising  from  the  lower  outer  margin  of  the  pedal  ganglion 
as  a  pedal  nerve.  According  to  my  preparations  and  sections  it 
is  a  nerve  from  the  cerebro-pleural  complex,  its  fibres  penetrating 
the  capsule  of  the  pedal  ganglion  at  the  upper  inner  border  of  the 
latter,  immediately  above  the  connectives  joining  the  pedal  gan- 
glion to  the  cerebro-pleural  complex.  The  fibres  do  not  enter 
the  pedal  ganglion,  however,  but  course  directly  into  the  pleural 
portion  of  the  cerebro-pleural  group.  A  similar  relation  may 
also  be  suspected  in  Sp.  inornata  in  the  case  of  the  nerve  num- 
bered 6,  in  fig.  36  of  PI.  Ill,  in  Vayssiere's  "Recherches  sur  les 
Mollusques  Opistobranches  du  Golfe  de  Marseille,  Supplement." 

A  decided  asymmetry  is  to  be  noticed  in  the  nerves  of  the 
pedal  ganglia  upon  the  two  sides.  Whether  this  has  any  special 
significance  or  not  could  not  be  determined  by  the  dissection  of 
but  one  specimen  alone. 

Counting  the  olfactory  stalk  as  a  nerve  we  have  seven 
nerves  given  off  from  the  cerebro-pleural  complex,  five  of  which 
arise  from  the  cerebral  portion,  one  from  the  intermediate  zone 
between  the  cerebral  and  the  pleural  regions,  and  one  from  the 
pleural  alone.  As  the  optic  and  otic  ganglia  are  sessile,  they  are 
not  included  in  the  above  enumeration.  From  the  pedal  ganglion 
two  large  nerves  arise,  which  are  distributed  to  the  sole  of  the 
foot.  The  peripheral  distribution  of  the  nerves  was  not  worked 
out  in  detail,  such  an  undertaking  requiring  much  more  material 
than  was  available. 

REPRODUCTIVE  SYSTEM. 

The  hermaphroditic  gland  is  made  up  of  eight  spherical 
lobules,  closely  packed  together  and  more  or  less  flattened  by 
mutual  pressure.  Six  of  these  are  paired,  alternating  more  or 
less  in  position,  while  the  seventh  and  eighth  are  unpaired.  The 
glans  penis  is  short  and  conical  and  entirely  unarmed.  The  re- 
maining organs  of  the  reproductive  system  are  not  greatly 
different  from  those  of  the  other  species  of  Spurilla,  all  of  which 
seem  to  show  close  similarity. 

The  general  differences  shown  by  this  specimen  in  anatomi- 
cal organization,  especially  as  shown  by  the  mandibles  and  radula, 


SPURILLA    BRAZILIANA    MAC  FARLAND  99 

seem  sufficient  to  authorize  its  recognition  as  a  member  of  a 
species  distinct  from  the  European  ones  already  described.  The 
name  Spurilla  brasiliana  is  here  proposed  for  it. 

Type  No.  149,  Invertebrate  Series,  Leland '  Stanford  Junior 
University  Zoological  Museum. 


LITERATURE. 

ADAMS,  ARTHUR. 

1854.     Monographs  of  Actaeon  and  Solidula.     Proceedings 

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1864.  Anatomiske  Bidrag  til  Kundskab  om  ^Eolidierne.  K. 
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1871.  Beitraege  zur  Kenntniss  der  Mollusken  des  Sargas- 
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18773.  Kritische  Untersuchungen  der  Ehrenberg'schen  Dori- 
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i877b.  Beitraege  zur  Kenntniss  der  yEolidiaden,  IV.  Verh. 
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i877c.  Malacologische  Untersuchungen,  XII,  in  Semper, 
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18783.  Neue  Nacktschnecken  der  Sudsee,  IV.  Journal  Mu- 
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601,  Taf.  LXII-LXV. 

18793.  Beitraege  zur  Kenntniss  der  ^Eolidiaden,  VI.  Verh. 
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i879b.  Die  Doriopsen  des  Atlantischen  Meeres.  Jahrb.  d. 
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i879c.  Ueber  die  Gattung  Peltodoris.  Mittheilungen  aus 
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1880.  Malacologische  Untersuchungen,   Supplementheft  I, 
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1881.  Malacologische  Untersuchungen,  Supplementheft  II, 
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LITERATURE 


101 


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754,  Taf.  LXIX-LXXVI. 
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Expedition,  X,  p.  1-154,  PL  I-XIV. 

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815-872,  Taf.  LXXXII-LXXXIV. 

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1892.  System  der  Nudibranchiaten  Gasteropoden.  Wies- 
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1894.  Die  Opisthobranchien.  Bulletin  Museum  of  Compara- 
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I-XII. 

1897.  Die  Pleurobranchiden,  I,  II.  Malacologische  Unter- 
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i898a.  Die  Opisthobranchier  der  Sammlung  Plate,  Zoolog. 
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i898b.  Malacologische  Untersuchungen,  IV,  I,  3, 1  c  p  117- 
158,  Taf.  IX-XII. 

1905.       Die     Opisthobranchiata     der     Siboga     Expedition. 

Leiden,  p.  1-248,  Taf.  I-XX. 
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1825.    Manuel  de  Malacologie  et  de  Conchyliologie.    Paris 
BOLOT,  E. 

1886.    Sur  le  Ponte  de  Doris.     Comptes  Rendus  Acad.  Sci. 

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1883.    Notes  on  the  Structure  and  Relations  of  the  Kidney 

in  Aplysia.    Mitth.  Zool.  Station  zu  Neapel,  IV,  p.  420- 

428,  PI.  30. 
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1803.    Memoire  sur  la  Genre  Laplysia.    Annales  du  Museum 

d'Histoire  Naturelle,  Paris,  II,  p.  287-314,  PI.  I-IV. 
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Annales  du  Museum  d'Histoire  Naturelle,  Paris  V    p 

266-276,  PI.  18. 


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OHL,  HERMANN. 

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1828.     Histoire  Naturelle  des  Aplysiens.     Paris. 


104 


OPISTHOBRANCHIATA  OF  BRAZIL 


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di  Bologna,  Ser.  Ill,  T.  V,  p.  1-8,  Tav.  MIL 

1878.     Anatomia  e   Fisiologia   della  Spurilla  neapolitana. 
Memorie  dell'  Accad.  Sci.  Istituto  di  Bologna,  Ser.  Ill, 
T.  IX,  p.  405-450,  T.  I-XII. 
VAYSSIERE,  A. 

1885.  Recherches  zoologiques  et  anatomiques  sur  les  Mol- 
lusques  Opistobranches  du  Golfe  de  Marseille,  I  Tecti- 
branches.  Annales  du  Musee  d'  Histoire  Naturelle  de 
Marseille,  Zoologie,  Memoire  3,  p.  1-181,  PI.  1-6. 

1888.  Ibid,  II,  Nudibranches  et  Ascoglosses.  1.  c.,  Ill, 
Memoire  4,  p.  1-160,  PI.  1-7. 

1903.  Ibid,  Supplement.  1.  c.,  VIII,  Memoire  3,  p.  73-108, 
PI.  II-III. 

1898.  Monographic  de  la  Famille  des  Pleurobranchides,  I, 
Annales  des  Sciences  Naturelles,  Zoologie,  (8),  VIII, 
p.  209-402,  PI.  13-28. 

1901.    Ibid,  II.    1.  c.,  (8),  XII,  p.  1-85,  PI.  I-VI. 
WATSON,  R.  B. 

1886  Report  on  the  Scaphopoda  and  Gasteropoda  collected 
by  H.  M.  S.  Challenger.  Zoology  Challenger  Expedi- 
tion, XV,  p.  i-v,  1-756,  PI.  I-L,  I-III. 

ZUCCARDI,  R. 

1890.  Intorno  all'  Anatomia  dell'  Apparato  digerente  nelle 
Aplysise  del  Golfo  di  Napoli.    Boll.  Soc.  Nat.  Napoli, 
JV,  p.  5-14,  T.  1-2. 


EXPLANATION    OF   PLATES. 


he  Ahhr  made 

.he  Abbe  Camera  Luada,  and  were  redrawn  in  ink  by  Olive  H. 

'  S. 


PLATE  I. 

Tethys  dactylomela  (Rang). 

Fig.  i.  Median  and  first  lateral  teeth  of  each  side  of  49th  and 
5Oth  rows  of  radula.  x  62. 

Fig.  2.  8th,  Qth  and  loth  lateral  teeth  of  49th  and  5oth  rows  of 
radula.  x  62. 

Fig.  3.  i8th,  I9th  and  29th  lateral  teeth  of  5oth  row  of  radula. 
x  62. 

Fig.  4.  Outermost  teeth,  the  32nd  to  37th  laterals  of  54th 
row.  x  62. 

Fig.  5.     A  single  typical  lateral  tooth,     x  no. 

Fig.  6.  Side  view  of  the  outer  face  of  5th  laterals  of  the  49th 
and  soth  rows,  x  62. 

Fig.  7.  Labial  armature  in  surface  view,  a,  anterior;  p,  poste- 
rior margin,  x  195. 


PLATE  II. 

Fig.  8.  Central  nervous  system  of  Tethys  dactylomela  (Rang). 
cer.  g.,  cerebral  ganglia;  ped.  g.,  pedal  ganglia;  pi.  g., 
pleural  ganglia ;  buc.  g.,  buccal  ganglia ;  c.  p.  con.,  cere- 
bro-pedal  connectives;  c.  pi.  con.,  cerebro-pleural  con- 
nectives; c.  b.  con.,  cerebro-buccal  connectives;  pi.  par. 
con.,  right  pleuro-parietal  connective;  pi.  v.  con.,  left 
pleuro-visceral  connective;  p.  com.,  pedal  commissure; 
p.  p.  com.,  parapedal  commissure. 

The  nerves  from  each  ganglion  are  numbered  ser- 
ially as  described  in  the  text,  and  are  distinguished  by 
the  prefixed  letter,  b.,  c.,  pi.,  or  p.,  indicating  their  repec- 
tive  ganglia,  buccal,  cerebral,  pleural  or  pedal,  x  10.5. 


PLATE  III. 
Figs.  9-14,  Tethys  dactylomela  (Rang). 

Fig.  9.  Buccal  ganglia  in  situ,  seen  obliquely  from  below  and 
the  right  side.  «.,  cut  end  of  esophagus;  s.  gl,  right 
salivary  gland,  its  severed  distal  end  bent  forward  and 
to  the  right ;  buc.  g.,  buccal  ganglia ;  c.  b.  con.,  cerebro- 
buccal  connective.  The  buccal  nerves  are  numbered 
serially  from  i  to  6.  In  this  specimen  the  5th  and  6th 
nerves  arose  from  a  common  trunk,  x  8. 

Fig.  10.  Buccal  ganglia,  ventro-posterior  face.  Lettering  as  in 
Fig.  9.  x8. 

Fig.  u.  Buccal  ganglia,  dorso-anterior  face.  Lettering  as  in 
Fig.  9.  x  8. 

Fig.  12  Posterior  margin  of  labial  armature  showing  outlines 
of  bases  of  the  rodlets.  x  223. 

Fig.  13.  Two  elements  of  the  labial  armature  from  anterior 
margin  of  plate,  x  137. 

Fig.  14.  Parieto-visceral  ganglion  complex,  r.  p.  g.,  right  parie- 
tal ganglion;  /.  v.  g.,  left  visceral  ganglion;  pi.  par. 
con.,  right  pleuro-parietal  connective;  pi.  v.  con.,  left 
pleuro-visceral  connective;  r.  p.  I.,  ist  parietal,  or  vulvar 
nerve;  ia.,  its  branch  forming  an  anastomosis  with  the 
branch  of  the  3rd  pedal  nerve  supplying  the  Organ  of 
Bohadsch;  r.  p.  2,  second  parietal,  or  osphradio-ctenidial 
nerve ;  /.  v.  i,  first  visceral  nerve  to  vesicle  of  Swammer- 
dam,  the  spermatocyst ;  /.  v.  2,  second  visceral  nerve; 
/.  v.  30,.,  and  /.  v.  $b.,  the  two  main  branches  of  the 
third  visceral  nerve,  in  some  specimens  arising  as  dis- 
tinct nerves,  in  others  branching  from  a  common  trunk. 
x8. 

Figs.  15-22,  Tethys  cervina  Dall  and  Simpson. 

Fig.  15.  Outline  of  labial  armature,  x  8. 

Fig.  16.  Rodlet  from  anterior  portion  of  labial  armature,    x  183. 

Fig.  17.    Surface  view  of  Organ  of  Bohadsch,  or  hypobranchial 

gland,    a.,  artery ;  i,  nerve  from  right  pedal  ganglion ; 

2,  nerve  from  left  visceral  ganglion,    x  6. 


Fig.  18.    Anterior  smaller  tooth  of  second  triturating  stomach 

obliquely  from  in  front,    x  24. 
Fig.  19.    Similar  tooth  in  lateral  view     x  24 
Fig.  20.    Larger  tooth  of  posterior  series,  obliquely  from  in 

iront.    x  24. 
Fig.  21.     Largest  tricuspid  tooth  of  posterior  series,  obliquely 

from  below,  showing  the  convex  basal  surface  with 

transverse  median  ventral  groove     x  24 
Fig.  22.     Typical    small,    conical   tooth    from   third  triturating 

stomach,     x  40. 


PLATE  IV. 
Tethys  cervina  Dall  and  Simpson 

Fig.  23.    Median  and  first  three  lateral  teeth  of  twentieth  and 

twenty-first  rows  of  radula.    x  62. 
Fig.  24.    Fourth  to  tenth  lateral  teeth  of  same  rows  of  radula. 

x62. 
Fig.  25.     Eleventh  to  twenty-second    (outermost)    lateral  teeth 

of  same  rows.    The  three  figures  of  this  plate  represent 

the  whole  extent  of  two  rows  of  teeth  from  the  middle 

to  the  side  of  the  radula.    x  62. 


PLATE  V. 
Tethys  cervina  Dall  and  Simpson. 

Fig.  26.    Median  and  first  lateral  teeth  on  either  side,  24th  and 

25th  rows  of  radula.    x  94. 
Fig.  27.    Sixth,  seventh  and  eighth  lateral  teeth,  24th  and  25th 

rows  of  radula.    x  94. 
Fig.  28.    Seven  outer  lateral  teeth  of  29th  and  3Oth  rows  of 

radula.    x  94. 
Fig.  29.    Detail  of  sixth  lateral  tooth  of  2Oth  row  of  radula. 

x  180. 
Fig.  30.    Detail  of  I4th  lateral  tooth  of  3Oth  row,  from  opposite 

side  of  radula.    x  180. 


PLATE  VI. 
Tethys  cervina  Dall  and  Simpson 

Fig.  31.  Alimentary  canal  from  below.  The  convolutions  of  the 
intestine  are  shown  in  their  natural  position,  the  liver 
having  been  dissected  away,  e.,  lower  end  of  the 
esophagus ;  ingl.,  ingluvies,  or  first  stomach ;  m.  St., 
muscular  band  of  second,  or  grinding  stomach;  j  st., 
third  stomach;  h.  coe.,  hepatic  coecum;  int.,  intestine. 

x  3- 

Fig.  32.  Relations  of  hepatic  coecum  and  bile  chamber.  The 
wall  of  the  lower  portion  of  the  third  stomach  and  the 
first  portion  of  the  intestine  have  been  cut  away,  show- 
ing the  entrance  of  the  large  ducts  of  the  liver  in  the 
opposite  wall.  The  substance  of  the  liver  itself,  which 
here  almost  entirely  incloses  the  alimentary  canal,  has 
been  dissected  away.  h.  coe.,  hepatic  coecum ;  /.  r.,  the 
prolongation  into  the  intestine  as  a  longitudinal  ridge 
of  one  of  the  folds  in  the  wall  of  the  hepatic  coecum. 

*5- 

Fig.  33.  Reproductive  system  seen  from  below,  the  right  border 
being  above  and  to  the  left.  ov.  t.,  ovotestis ;  sm.  h.  d., 
small  hermaphroditic  duct;  sp.  c.,  spermatocyst ;  d.  c., 
duct  of  Cuvier;  sp.  p.,  spiral  portion  of  genital  duct; 
c.  p.,  convoluted  portion  of  genital  duct ;  ov.  sp.  d.,  ovo- 
spermatic  duct ;  cop.  d.,  copulatory  duct ;  spth.,  sperma- 
totheca;  d.  spth.,  its  duct;  in.,  flap  of  the  integument, 
upon  the  external  face  of  which  lies  the  vulvar  aperture ; 
g.  g.,  genital  ganglion;  /.  v.  3.,  third  nerve  from  left 
visceral  ganglion,  x  8. 


PLATE  VII. 

Fig.  34.  Central  Nervous  System  of  Tethys  cervina  Dall  and 
Simpson,  in  dorsal  view.  cer.  g.,  cerebral  ganglia; 
ped.  g.,  pedal  ganglia ;  pi.  g.,  pleural  ganglia ;  c.  p.  con., 
cerebro-pedal  connective;  c.  pi.  con.,  cerebro-pleural 
connective;  pi.  par.  con.,  right  pleuro-parietal  con- 
nective; pi.  v.  con.,  left  pleuro-visceral  connective;  p. 
com.,  pedal  commissure ;  s.  c.  c.,  sub-cerebral  commis- 
sure; p.  p.  com.,  parapedal  commissure.  The  nerves 
are  numbered  serially  in  the  order  of  their  origin  from 
each  ganglion.  Those  of  the  pleural  ganglia  are  des- 
ignated pi.  i,  and  pi.  2;  those  of  the  cerebral  ganglion 
by  the  prefix  c  to  their  respective  numbers,  while  the 
nerves  of  the  pedal  ganglia  are  designated  by  numerals 
alone,  x  Anastomosis  of  a  branch  of  the  third  cere- 
bral nerve,  c.  3,  of  the  right  side  with  a  branch  of  the 
second  pedal,  2.  e.,  eye.  x  18. 


PLATE  VIII. 

Fig.  35-  Parieto-visceral  ganglia  and  nerves  of  Tethys  cervina 
Dall  and  Simpson.  The  contours  of  the  Organ  of 
Bohadsch,  o.  B.,  and  the  pericardial  cavity,  per.  c.,  are 
indicated  in  dotted  lines,  that  of  the  reproductive  sys- 
tem in  light  lines  and  unshaded.  The  anterior  end  of 
the  animal  is  directed  toward  the  upper  side  of  the 
plate,  the  right  of  the  animal  corresponds  to  the  left  of 
the  plate,  the  preparation  being  drawn  in  ventral  view. 
r.  pi.  par.  con.,  right  pleuro-parietal  connective ;  /.  p.  v. 
con.,  left  pleuro-visceral  connective;  par.  v.  g.,  the 
parieto-visceral  ganglion  complex,  the  ventral,  or  vis- 
ceral moiety  concealing  the  upper  parietal  portion; 
r.  p.  I.,  vulvar  nerve  of  right  parietal  ganglion,  bifurcat- 
ing into  ia.,  which  anastomoses  with  a  branch  of  the 
third  pedal  nerve,  3  ped.,  and  ib.}  the  vulvar  nerve 
proper;  r.  p.  2,  osphradio-ctenidial  nerve;  osp.  g.,  os- 
phradial  ganglion ;  o.  g.  I.,  nerve  to  mantle ;  ct.  g.,  cteni- 
dial  ganglion ;  /.  v.  2.,  second  nerve  of  left  visceral  gang- 
lion ;  2a.,  its  hepatic  branch ;  2b.,  its  main  branch  forking 
to  siphon  and  anus ;  20.,  its  recurrent  branch  to  the  peri- 
toneum and  the  organ  of  Bo j anus,  anastomosing  beyond 
the  latter  with  a  branch  of  the  third  pedal  nerve;  3 
ped.,  of  the  right  side;  2d.,  its  branch  to  the  posterior 
peritoneum,  etc.;  2e.,  the  branch  to  the  organ  of  Bo- 
janus;  /.  v.  3.,  third  nerve  of  left  visceral  ganglion, 
supplying  g.  g.,  the  genital  ganglion,  and  dividing  into 
v.  sa.,  and  v.  $b.,  to  the  small  hermaphroditic  duct  and 
ovotestis,  and  to  the  dorsal  body  wall  respectively,  other 
delicate  minor  branches  noted  in  the  text  not  being  rep- 
resented. /.  v.  4.,  fourth  nerve  of  left  visceral  ganglion, 
4a.  its  branch  to  ventricle  and  pericardium,  $.  its 
branch  to  kidney,  pericardium  and  auricle.  3  ped., 
main  trunk  of  third  pedal  nerve  of  right  side,  bifurcat- 
ing into  ja  and  j&.  ja  gives  off  $c  to  the  organ  of 
Bohadsch,  and  $f,  which  anastomoses  with  a  branch 
of  the  vulvar  nerve,  ia,  and  is  distributed  to  the  muscles 
of  the  body  wall.  56  sends  off  $d  to  the  right  retractor 


muscle  of  the  head,  and,  as  ^e,  anastomoses  with  the 
recurrent  branch  of  the  second  nerve  of  the  left  visceral 
ganglion,  sc.  sin.  h.  d.,  small  hermaphroditic  duct; 
ad.  g.  m.,  adnexed  genital  mass;  sp.  c.,  spermatocyst ; 
/.  h.  d.,  large  hermaphroditic  duct;  spth.f  spermato- 
theca.  x  8. 


PLATE  IX. 

Fig.  36.    Diagram  of  Central  Nervous  System  of  Tethys  punc- 

tata  (Cuv.),  seen  from  below,  after  Mazzarelli. 
Fig.  37.    Diagram  of  Central  Nervous  System  of  Tethys  depilans 

(Linn),  seen  from  below,  after  Mazzarelli. 
Fig.  38.    Diagram  of  Central  Nervous  System  of  Tethys  dacty- 

lomela  (Rang),  seen  from  below. 
Fig.  39.     Diagram  of  Central  Nervous  System  of  Tethys  cer- 

vina  Dall  and  Simpson,  seen  from  below. 

The  following  abbreviations  apply  to  all  the  figures  of  this 
plate:  c.  g.,  cerebral  ganglia;  p.  g.,  pedal  ganglia;  pi.  g.,  pleural 
ganglia;  /.  v.  g.,  left  visceral  ganglion,  fused  more  or  less  com- 
pletely with  its  fellow,  the  right  parietal  ganglion ;  o.  B.}  organ  of 
Bohadsch,  or  hypobranchial  gland;  3p.,  third  pedal  nerve,  a,  its 
branch  anastomosing  with  the  right  parietal  ganglion,  b,  its 
branch  to  the  organ  of  Bohadsch,  c,  its  branch  or  branches  to  the 
muscles  of  the  body  wall,  m,  also  in  figs.  38  and  39  anasto- 
mosing with  the  recurrent  branch,  20,  of  the  second  nerve,  /.  v.  2, 
from  the  left  visceral  ganglion ;  20,,  hepatic  branch  of  second  vis- 
ceral nerve,  2}),  its  main  trunk  to  siphon  and  anus. 


T.  piwctata  (Cuv.)  T.   depiUins   (Linn.) 

36  LL  37 


3P 


T.  dactylomela   (Rang) 


T    ceriina  D    &  S 


38 


c-g 


PLATE  X. 
Tethys  cervina  Dall  and  Simpson. 

Fig.  40.    Dorsal  view  of  shell,    x  46. 

Fig.  41.  Outline  sketch  of  preserved  specimen  in  dorsal  view, 
mainly  intended  to  show  the  general  proportions  and 
the  markings  surrounding  the  mantle  pore.  Tentacles 
and  rhinophores  strongly  contracted,  the  head  itself 
less  so.  x  2. 

Fig.  42.  Detail  of  parieto-visceral  ganglion  complex  from  above, 
the  two  fused  ganglia  being  rotated  into  side  view,  and 
all  the  nerves  being  more  or  less  displaced  to  show 
their  mutual  relations,  pi.  p.  con.,  pleuro-parietal  con- 
nective; pi.  v.  con.,  pleuro-visceral  connective;  r.  p.  g., 
right  parietal  ganglion;  /.  v.  g.,  left  visceral  ganglion; 
r.  p.  i,  vulvar  nerve;  r.  p.  ia.,  its  branch  anastomosing 
with  the  third  pedal  nerve ;  r.  p.  ib.,  its  branch  to  an- 
terior end  of  large  hermaphroditic  duct;  r.  p.  2,  os- 
phradio-ctenidial  nerve;  osp.  g.,  osphradial  ganglion 
together  with  a  portion  of  the  integument  cut  out  from 
the  body  wall;  ct.  g.,  ctenidial  ganglion;  osp.  g.  I, 
nerve  to  anterior  and  lateral  regions  of  the  mantle; 
ct.  n.,  main  ctenidial  nerve;  /.  v.  I,  nerve  to  vesicle  of 
Swammerdam,  or  spermatocyst,  and  its  duct;  /.  v.  2, 
I.  v.  3,  /.  v.  4,  second,  third  and  fourth  nerves  from  the 
left  visceral  ganglion,  x  20. 


PLATE  XI. 
Pleurobranchus  agassizii  MacFarland. 

Fig.  43.     Shell  in  dorsal  view,    x  15. 

Fig.  44.  Dorsal  view  of  loth,  nth,  and  I2th  elements  of  labial 
armature  from  8th  to  loth  rows,  x  240. 

Fig.  45.  Ventral  view  of  elements  of  labial  armature  from  near 
margin  of  65th  and  66th  rows,  x  372. 

Fig.  46.  Ventral  view  of  bases  of  elements  of  labial  armature 
from  middle  portion.  At  this  focus  the  hook  and  den- 
ticles are  not  seen,  x  240. 

Figs.  47,  48.  Lateral  views  of  isolated  elements  of  labial  arma- 
ture, x  372. 

Fig.  49.  Outermost  lateral  teeth  of  eleventh  row  of  radula. 
x  450. 

Fig.  50.  Twenty-first  and  twenty-second  lateral  teeth  of  22d  row 
of  radula.  x  450. 

Fig.  51.  1 6th,  17th,  and  i8th  teeth  of  I9th  row  of  radula,  ob- 
liquely from  above,  x  450. 

Fig.  52.  ist,  2nd,  and  3rd  lateral  teeth  of  I9th  row  of  radula, 
obliquely  from  above,  x  450. 

Fig-  53-  Ventral  view  of  bases  of  iTth  to  2ist  lateral  teeth  of 
nth  row  of  radula.  x  450. 

Fig.  54.  Lateral  view  of  glans  penis  and  vaginal  opening  from 
below,  v.,  vaginal  opening,  x  12. 


PLATE  XII. 

Figs.  55-57.    Pleurobranchus  agassizii  MacFarland. 

Fig.  55.  Dorsal  view  of  ganglia  of  Central  Nervous  System, 
the  nerves  and  ventral  commissures  not  being  repre- 
sented, c.  pi.  g.,  cerebro-pleural  ganglion ;  p.  g.}  pedal 
ganglion;  c.  p.  con.,  cerebro-pleural  connectives;  pi.  p. 
con.,  pleuro-pedal  connectives ;  e.,  eye  and  optic  gang- 
lion. .  x  28. 

Fig.  56.  Outline  of  mandibular  armature,  d.,  dorsal  margin; 
a.,  anterior  margin ;  v.,  ventral  margin,  x  28. 

Fig.  57.     Ventro-lateral  view  of  right  rhinophore.     x  12. 

Figs.  58-65.     Discodoris  branneri  MacFarland. 

Fig.  58.     Mandibular  armature,    x  30. 

Fig.  59.    Anterior  rodlets  of  mandibular  armature,    x  214. 

Fig.  60.     Posterior  rodlets  of  mandibular  armature,     x  214. 

Fig.  61.  Outermost  lateral  teeth  of  i6th  row  of  radula  in  side 
view,  x  1 20. 

Fig.  62.  Outermost  lateral  teeth  of  7th  row  of  radula,  in  side 
view,  x  1 20. 

Fig.  63.  Typical  lateral  tooth  from  5th  row,  in  side  view  of  inner 
face,  x  214. 

Fig.  64.  Hooks  of  armature  of  glans  penis,  a,  in  side  view;  b, 
in  front  view,  x  214. 

Fig.  65.  Reproductive  organs  from  above,  the  parts  slightly  dis- 
placed so  as  to  show  their  mutual  relations,  h.  d., 
hermaphroditic  duct;  h.  amp.,  hermaphroditic  ampulla; 
sp.  d.,  spermatic  duct ;  ov.  d.,  oviduct ;  pr.  g.,  prostate 
gland ;  v.  d.,  vas  deferens ;  p.,  glans  penis ;  n.  a.  c., 
nidamental-albumen  gland  complex;  n.  d.,  duct  of  nid- 
amental  gland ;  u.  d.,  uterine  duct ;  sp.  c.,  spermatocyst ; 
spth.,  spermatotheca ;  vag.,  vagina,  passing  over  prox- 
imally  into  the  vaginal  duct,  its  distal  portion  laid  open 
by  a  triangular  incision,  x  10. 


PLATE  XIII. 
Discodoris  voniheringi  MacFarland. 

Fig.  66.  Labial  armature,  a,  median;  b,  lateral  plates;  c,  an- 
terior border,  x  37. 

Fig.  67.  Front  view  of  three  typical  lateral  teeth  of  first  row 
of  radula.  x  212. 

Fig.  68.  Front  view  of  three  typical  lateral  teeth  from  middle 
of  first  row  of  radula.  x  212. 

Fig.  69.  Outermost  lateral  teeth  of  nth  row  of  radula,  ob- 
liquely from  above,  x  212. 

Fig.  70.  Outline  of  cross-section  of  nidamental  duct,  d,  dorsal ; 
v,  ventral  ridge;  g,  groove  between  them,  x  50. 

Fig.  71.  Reconstruction  from  serial  sections  showing  detailed 
relations  of  the  ducts  of  the  anterior  genital  mass.  h.  a., 
anterior  end  of  hermaphroditic  ampulla  as  it  enters  the 
nidamental-albumen  gland  complex;  sp.  d.,  spermatic 
duct  emerging ;  n.  d.,  nidamental  duct ;  spth.,  spermato- 
theca;  u.  d.,  uterine  duct;  sp.  c.,  spermatocyst,  with  its 
duct,  spc.  d.,  leading  into  the  uterine  duct;  vag.  d., 
vaginal  duct,  cut  off  short  to  show  the  relations  of  the 
underlying  organs.  The  dotted  oval  upon  the  surface 
of  the  nidamental  gland  indicates  the  approximate 
boundary  of  the  albumen  gland. 


66 


67 


6Q 


spth 


71 


PLATE  XIV. 
Discodoris  voniheringi  MacFarland. 

Fig.  72.  Reconstruction  from  serial  sections  showing  the  mu- 
tual relations  of  the  principal  ducts  and  cavities  within 
the  nidamental-albumen  gland  complex.  The  less  im- 
portant branches  and  all  of  the  secretory  alveoli  of  the 
glands  have  been  omitted,  and  are  to  be  thought  of  as 
filling  the  space  between  the  ducts  represented  and  the 
dotted  line,  which  indicates  the  external  contour  of  the 
gland  complex,  as  seen  in  side  view.  h.  amp.,  the  distal 
end  of  the  hermaphroditic  ampulla  as  it  enters  the 
gland;  i.  h.  a.,  its  intraglandular  portion,  dilating  into 
/.  ch.,  the  fertilization  chamber;  u.  d.,  uterine  duct; 
/.  alb.,  lumen  of  albumen  gland;  x.,  duct  connecting 
intraglandular  portion  of  hermaphroditic  ampulla  with 
the  lumen  of  albumen  gland;  alb.  d.,  albumen  gland 
duct  connecting  the  albumen  gland  with  the  lumen  of 
the  nidamental  gland;  /.  nid.,  lumen  of  nidamental 
gland ;  n.  d.,  nidamental  duct,  cut  across  as  it  leaves  the 
gland.  The  cut  end  represents  the  thickness  of  the  epi- 
thelial lining  of  the  duct  only,  x  165. 

Figs.  73  and  74.  Ventral  and  dorsal  views  respectively  of  the 
reproductive  complex.  All  connective  tissue,  nerves  and 
blood  vessels  have  been  omitted  for  the  sake  of  clear- 
ness, h.  d.,  cut  end  of  hermaphroditic  duct;  h.  amp., 
hermaphroditic  ampulla;  sp.  d.,  spermatic  duct;  n.  g., 
nidamental-albumen  gland  complex;  nid  d.,  nidamental 
duct ;  vag.,  vagina ;  vag.  d.,  vaginal  duct ;  u.  d.,  uterine 
duct;  spth.,  spermatotheca ;  spc.,  spermatocyst ;  pr.  g., 
prostate  gland;  v.  d.,  vas  deferens;  p.,  penis;  p.  o.,  ex- 
ternal opening  of  praeputium;  v.  o.,  external  vaginal 
opening;  n.  d.  o.,  external  opening  of  nidamental  duct. 


73 


PLATE  XV. 

Figs.  75-76.     Discodoris  voniheringi  MacFarland. 

Fig.  75.    Side  view  of  typical  lateral  tooth  from  near  center  of 

ist  row  of  radula.     x  244. 
Fig.  76.     Four  lateral  teeth  from  inner  end  of  i6th  row,  slightly 

displaced,    x  244. 

Figs.  77-82.    Peltodoris  greeleyi  MacFarland. 

Fig.  77-     Two  typical  spicules  from  dorsum.    x  244. 

Fig.  78.  Oblique  view  of  base  of  typical  lateral  tooth  of  radula. 
x  282. 

Fig-  79-  Outermost  lateral  teeth  of  I9th  and  2Oth  rows  of 
radula.  x  244. 

Fig.  80.     Innermost  lateral  teeth  of  I7th  row  of  radula.    x  244. 

Fig.  81.     Typical  lateral  tooth  of  radula  in  side  view,    x  282. 

Fig.  82.  Portion  of  anterior  genital  complex,  the  nidamental 
and  albumen  glands  having  been  removed,  h.  d.,  an- 
terior end  of  hermaphroditic  duct;  h.  amp.,  hermaph- 
roditic ampulla ;  sp.  d.,  spermatic  duct  entering  prox- 
imal end  of  large  prostate  gland,  pr.;  u.  d.,  uterine  duct, 
receiving  the  duct  of  the  spermatocyst,  spc.,  and  cut  off 
just  before  its  entrance  into  the  nidamental  gland; 
spth.,  spermatotheca ;  vag.  d.,  vaginal  duct,  its  distal 
portion  severed  just  before  it  dilates  into  the  vagina; 
v.  def.,  proximal  portion  of  vas  deferens.  x  10. 


PLATE  XVI. 

Spurilla  braziliana  MacFarland. 

Fig.  83.  Twelfth  tooth  of  radula.    x  116. 

Fig.  84.  First  tooth  of  radula.    x  116. 

Fig.  85.  Anterior  end  of  foot  in  ventral  view,  the  extruded 

mouth  region  showing  above,     x  5. 

Fig.  86.  Left  salivary  gland  in  side  view,    x  10. 

Fig.  87.  Right  salivary  gland  in  side  view,    x  10. 

Fig.  88.  Anal  papilla,    x  10. 

Fig.  89.  Median  portion  of  typical  tooth  of  radula.    x  146. 


83 


PLATE  XVII. 

Spurilla  braziliana  MacFarland. 

Figs.  90  and  91.  Outline  sketches  of  preserved  specimen  from 
left  and  right  sides.  The  dorso-lateral  cereta  have  all 
been  removed,  the  outline  of  their  bases  showing  their 
relative  position.  The  mouth  region  and  reproductive 
openings  are  partly  everted  and  much  distorted,  and 
the  rhinophores  are  strongly  contracted,  x  5. 

Figs.  92  and  93.  Inner  surfaces  of  left  and  right  mandibles,  a., 
superior  margin ;  b.,  inferior  margin ;  c.,  posterior  tip  of 
masticatory  process;  d.,  fulcrum,  or  hinge,  with  single 
crest  in  left  mandible;  e.,  the  same,  with  double  crest 
in  right  mandible,  x  16. 


PLATE  XVIII. 
Spurilla  braziliana  MacFarland. 

Fig.  94.  Detail  of  head,  or  hinge  region  of  right  mandible,  inner 
surface,  a.,  superior  margin;  b.,  inferior  margin;  c., 
the  fulcrum,  bearing  double  longitudinal  crests  bound- 
ing a  longitudinal  groove,  into  which  the  single  crest 
of  the  left  mandible  fits ;  d,  ventral  margin  of  the  an- 
terior portion  of  the  masticatory  process,  x  45. 

Fig.  95-  Detail  of  head  region  of  left  mandible,  inner  surface. 
Lettering  as  in  preceding  figure.  The  fulcrum,  c., 
bears  a  single  crest,  x  45. 


PLATE  XIX. 
Spurilla  braziliana  MacFarland. 

Fig.  96.  Central  Nervous  System  from  above.  The  buccal  and 
olfactory  ganglia  are  not  shown;  the  basal  ends  of  the 
olfactory  nerves,  olf.  n.,  are  seen  arising  from  the  cere- 
bral portion  of  the  cerebro-pleural  ganglion  complex, 
c.  pi.  g.  The  nerves  are  indicated  in  Roman,  I-VIII, 
in  uniformity  with  the  figures  of  Trinchese,  cited  in  the 
text.  ped.  g.,  pedal  ganglia;  ped.  coin.,  pedal  com- 
missure; pi.  com.,  pleural  commissure;  cer.  buc.  con., 
cerebro-buccal  connective;  e.,  eye;  ot.,  otocyst,  in  front 
and  slightly  beneath  it  the  otic  ganglion,  x  46. 


r     5 


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MacFarland,  Frank  Mace 

The  opisthobranchiate 
Mollusca  of  the  Branner- 
Agassiz  expedition  to 
Brazil. 


UC  SOUTHERN  REGIONAL  LIBRARY  FACILITY 

IN  II II 1 1  III  1 1  III 

A     000667600     1 


B8M2        MacFarland,  Frank  Mace 


opisthobranchiate 
Mollusca  of  the  Branner- 
expedition  to 


AGRICULTURAL  LIBRARY 

CITRUS  RES£AYR0CHCCLENTFR      ,, 
AGRICULTURAL  EXPERIMENT  STAIrO 
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